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FANTASY CENTRAL (February 21, 2004)

Posted 6:32 p.m., February 22, 2004 (#6) - Nod Narb(e-mail)
  I've got a project in the works that is a real time draft advisor.

I have the prototype up and running successfully as a VB macro in Excel, but I would be interested in collaborating with someone who has programming skills to turn it into an actual executable file. If you have any interest in taking my idea and turning it into code, feel free to email me for more details.

FANTASY CENTRAL (February 21, 2004)

Posted 9:20 p.m., February 22, 2004 (#10) - Nod Narb(e-mail)
  Nord, how did you get your equations?

I'm assuming this was directed towards me?

Anyway, I use a combination of standard deviations and linear weights based on factors such as positional scarcity and category quotas. This gives me an output of which player would be best to draft based on who has been drafted and who's left to draft. All of the values update in real time, as I tell the program who was drafted. Works fine in Excel, but would be much less cumbersome as a a web applet or an executable file.

Since I'm actually in a Primer-based league, I don't want to discuss all of the details here. I'd be more than happy to exchange emails though.

FANTASY CENTRAL (February 21, 2004)

Posted 1:16 p.m., February 24, 2004 (#27) - Nod Narb(e-mail)
  So does this say that ESPN's ratings are good?

One problem I've tried to deal with beyond figuring out who has the most value is the process of drafting based on these values. Some of the issues I am trying to improve on:

With each pick, a number of factors contribute to the decision of who to draft:

Who you drafted previously - this influences contributions to stat categories and position. For example, if you have drafted 3 HR hitters with your first three picks, your fourth pick might be better off being a guy with a lot of stolen bases, even if the higher HR guy has more overall fantasy value. Also, if you have drafted 3 OFs with your first 3 picks, drafting an OF with your 4th pick is probably inferior to drafting a good 1B, even if the OF has more overall fantasy value.

Who is left to pick from - if there are 3 good SS left and 3 good 2B left, who do you pick?

What has been picked by your opponents - ties in with above. If all of your opponents have a SS already, but 6 are looking for a 2B, you're better off drafting a 2B and waiting for a SS, even if the SS you would have picked has more fantasy value.

Picking pitchers vs. hitters - should a pick be spent on a hitter or a pitcher? Many factors play into this, including those listed above. Going strictly by fantasy value may not be productive in the whole scheme of things.

The real challenge is weighting all of these factors to make the optimal pick in each round. I have always tried to do this subjectively, with pretty good success. But there is no doubt that a system that takes all of this into account could be very beneficial. The VB macro I have created tries to do this, although I'm not sure I can test it to see if it's any better than what I would do without it.

I used Score Bard's draft simulator in conjunction with my applet to do a mock draft. I was becoming very frustrated when each and every round I was not drafting starting pitching. Halfway through the draft, I had only drafted 2 SPs. After the draft was completed, I found out why. There were not nearly as many SPs drafted as I had expected. Therefore, there were a lot of good SPs left in the latest rounds. Had I conducted the draft myself, I would have grabbed a lot more SPs earlier on, and thus losing out on all the offense I ended up getting, without sacrificing my pitching. I'm sure many points along the way I drafted someone without the highest fantasy value available.

Enough rambling...the moral here is that accurate fantasy values are good, but unless you have a good system of drafting that takes into account multiple variables, you may not draft successfully.

Thoughts?

FANTASY CENTRAL (February 21, 2004)

Posted 1:36 p.m., February 24, 2004 (#31) - Nod Narb (homepage)
  Well, I think the draft has to be a little subjective and surprising b/c that's some of the fun.

True, but I also have fun thinking about this kind of stuff (pathetic, yes). Anyway, you can take it or leave it, but I think at least considering being objective is useful, at least to some.

More teams are w/in .5 stds of the mean win number than you'd expect but I'm not sure how meaningful that is. Is there an excel function to test for "normalcy"?

See homepage

FANTASY CENTRAL (February 21, 2004)

Posted 1:40 p.m., February 24, 2004 (#32) - Nod Narb
  btw, Nod, I think ideally the draft software would tell you how far away from the mean you're projected to be in each category and either re-rank the players

Exactly. That's part of it.

Fine, but how do you make this stuff work in the playoffs? :)

You ELIMINATE the playoffs (muahaha).

A few years ago my league's format was head-to-head, meaning that the last 4 weeks of the regular season were the fantasy playoffs. I had a good 26 game lead on 2nd place at the end of the regular season, but on the last day of the first round of the playoffs, my opponent's team hit something like .750/.850/2.000 with 9 HRs, etc. and I was knocked out. As commissioner, I made sure that next year we had no playoffs :)

FANTASY CENTRAL (February 21, 2004)

Posted 2:29 p.m., February 24, 2004 (#37) - Nod Narb
  z-scores? if the z-score is just (wins- mean wins)/ stdv then z-score v. wins has to be a straight line. I think I need more coaching. I'll try to figure out how to get z-scores

not wins minus mean wins, just wins.

in excel, you can calculate z-scores as follows:

underneath the last value in the wins column, type in =average(Cx:Cy) and in the cell underneath that type =stdev(Cx:Cy) where C is the wins column and x and y are the first and last rows of data in your column.

now, in the first blank column to the right of your data, go to the topmost cell of data (usually the second row if you have data labels in the first row). type in =standardize(w,a,s)

in this case, w represents the cell in the wins column for the row you are in. a represents the cell that contains the average wins, and s represents the cell that contains the stdev of the wins column. You'll need to put a $ before the cell number in a and s and then fill down the column.

Thats really hard to explain in writing.

FANTASY CENTRAL (February 21, 2004)

Posted 2:31 p.m., February 24, 2004 (#38) - Nod Narb
  Heh. What a waste of time. Your calculation does the same thing. My bad.

FANTASY CENTRAL (February 21, 2004)

Posted 3:31 p.m., February 24, 2004 (#42) - Nod Narb
  J. Cross -

Can you run the correlation between team fantasy value (using your equations) and team rotopoints?

FANTASY CENTRAL (February 21, 2004)

Posted 8:58 p.m., February 25, 2004 (#65) - Nod Narb(e-mail)
  Well, I just had my first draft of the season. This was a public 5x5 yahoo league, just to test out my draft strategy. I was pretty pleased with the draft, although midway through I noticed that I mistyped one number leading to the overvaluation of SPs, so I drafted a few SPs before I should have.

12 teams, 21 rounds, total of 252 players
Offensive stats: R, HR, RBI, SB, AVG
Pitching stats: W, SV, K, ERA, WHIP

I had the 7th pick (serpentine draft)

Results (in order):
Bonds
Pudge
Randy
Giambi
Dotel
J. Santana
Rollins
Oswalt
Walker
Beckett
Webb
Green
Contreras
Durham
M. Batista
Rhodes
Spiezio
Floyd
Bernie
Klesko
Koch

A few notes: personally, I never would have drafted pudge, rollins, or spiezio as high as I did, but they were the best available at their position by a large margin at the time i selected them. I used marcel's predictions in my draft applet. I was totally shocked to get floyd, bernie, and klesko at the end of the draft. people had drafted so many terrible outfielders before them. all in all, I'm pleased but I have had better drafts without using my applet.

FANTASY CENTRAL (February 21, 2004)

Posted 9:02 p.m., February 25, 2004 (#66) - Nod Narb
  Walker is larry

FANTASY CENTRAL (February 21, 2004)

Posted 3:06 p.m., February 28, 2004 (#74) - Nod Narb
  MLB has a new fantasy service this year called Fantasy Ticket. It looks really damn cool.

http://mlb.mlb.com/NASApp/mlb/mlb/subscriptions/fantasy_ticket.jsp

FANTASY CENTRAL (February 21, 2004)

Posted 8:50 p.m., March 1, 2004 (#82) - Nod Narb (homepage)
  Sam thing applies to stats, i.e., if you already have a lot of steals, and Carl Crawford is the best available player left on the board, take him and trade him later on.

Do people agree with this line of thinking? I guess it really depends on your confidence in your trading ability...

I tend to agree with J. Cross and Kyle S. If Crawford was the best player available by 100%, I would definitely take him. But if he's only 5% better than a player at a position I don't already have, I'm taking the other guy. I've seen guys try to stock up on catchers at the beginning of drafts, but it never works out, because their need to fill the other positions is greater than others' desire to add another catcher. So they get antsy and trade their catchers for lesser value.

Say you took tejada with the 30th pick. if you want a better player in trade, you can't trade him for one of the first 29 players drafted, because obviously their managers chose to pass on tejada for the player they picked. if you think someone after the 30th pick is better than tejada, you're better off drafting him at 30 instead of hoping you get them in trade.

btw, does anyone know whether the difference in predicting pitchers for 2003 btw PECOTA and others was significant or could it have just been luck?

Well, not many people agree with me on this one, but IMO correlations here are pretty much useless. The best stat they report is RMSE - the average difference between projected stats and actual stats. Check out the homepage link. Because the error bars (RMSE) overlap in all cases, this indicates no statistically significant differences. This is not to say that PECOTA isn't better, it's just not significantly better.

The more statistically savvy can correct me if I'm wrong about this.

FANTASY CENTRAL (February 21, 2004)

Posted 11:32 a.m., March 2, 2004 (#84) - Nod Narb
  That is what's going on. The error bars represent RMSE. They only look the same because the range of RMSE between groups is quite small (.85 to .98 for OPS, 1.11 to 1.24 for ERA) relative to the scale of the graph. The key point is that they overlap, which, unless I'm mistaken (and I tend to be mistaken quite a bit), means that they aren't significantly different. Maybe I can put together two separate graphs so there's better resolution.

FANTASY CENTRAL (February 21, 2004)

Posted 12:26 p.m., March 2, 2004 (#86) - Nod Narb
  The implication of this statement is that if you had a league OPS in 1984,85,86 of .730,.730,.730, you would expect .730 for the league in 1987. We know that 1987 was not like the others. Say it was .770.

If you had Tim Raines at .830,.830,.830 in those 3 years, you might project him at .820 or something in 1987. If he ended up being .860, you'd think you were off by .040. But, everyone in the league would be off by that.

But if everyone's league average predictions were off by .04, then RMSE would still show whose predictions were closest (it would just be larger than it should be- but for everyone). And if you happen to do a better job at predicting the league average, the RMSE will go down even more. You should be rewarded for that.

FANTASY CENTRAL (February 21, 2004)

Posted 2:02 p.m., March 2, 2004 (#90) - Nod Narb
  No, because how can you predict 1987?

You can't (at least with a high degree of confidence). But at least this puts all projection systems on equal footing to start. As long as the starting point is equal for all systems, RMSE will be unbiased.

I think the discrepancy here is as follows:

You're arguing that a forecasting system should be graded based on the RMSE of normalized stats - that is, how far a player's predicted normalized stats are from his true normalized stats.

I'm arguing that a forecasting system should be judged based on the RMSE of raw stats - that is, how far a player's predicted raw stats are from his true raw stats.

Let's say we use your criterion. If a system does a good job predicting normalized stats, that tells us NOTHING about how close the raw stats are to matching reality.

Using my criterion, if a system does a good job predicting raw stats, then by definition it does a good job predicting normalized stats, because normalized stats (whether projected or real) are based on the raw stats from which they are derived.

My criterion sets a higher standard for success. Successful prediction of normalized stats does not guarantee successful prediction of raw stats.
However, successful prediction of raw stats DOES guarantee successful prediction of normalized stats. A system that is good at predicting both is better than a system that is only good at predicting normalized stats.

FANTASY CENTRAL (February 21, 2004)

Posted 2:13 p.m., March 2, 2004 (#91) - Nod Narb
  I agree that for fantasy purposes normalized stats are perfectly acceptable, as long as the rank order is reasonably accurate. Maybe we're not agreeing because I am thinking outside the realm of fantasy.

Think about it. You open up a book from 2002 and see that Bobby Abreu was predicted to hit .260/.360/.470. You say "that prediction was terrible! It was way off!"

However, in a system relying on normalized stats, that projection could have worked out to a perfect *OPS+ prediction of 155 (depending on the league average).

Personally, I would rather see the raw stats be more accurate than the normalized stats. And I can't see how accurate raw stats would reduce the accuracy of the normalized stats by any meaningful margin.

FANTASY CENTRAL (February 21, 2004)

Posted 5:55 p.m., March 5, 2004 (#110) - Nod Narb(e-mail)
  J. Cross,

If you'd like to "trade" spreadsheets, it might be useful for each of us to get an inside look at what the other is doing. They sound very similar.

FANTASY CENTRAL (February 21, 2004)

Posted 8:17 p.m., March 11, 2004 (#121) - Nod Narb
  Say in your draft you have to choose between two players:
Player 1 is 22 R, 5 HR, 15 RBI, 4 SB and .002 BA above replacement
Player 2 is 16 R, 4 HR, 21 RBI, 5 SB, and .005 BA above replacement level. Who do you pick?

Just knowing value above replacement is not enough. You need to use SDs to scale each category equally. This is especially important when comparing pitchers to hitters.

FANTASY CENTRAL (February 21, 2004)

Posted 6:54 p.m., March 15, 2004 (#128) - Nod Narb
  An alternative method is to use standard deviations. You have to get by the assumption that the player values are normally distributed (and if they're not you can always transform them), but it's a great way to answer the question you're asking. If Gagne's an 8, the average closer is a 3, and the SD is 2, then you know Gagne is 2.5 SD above the mean. If Vlad is a 17 and the average OF is a 10 with a SD of 3, then you know Vlad is 2.333 SD above the mean. If these numbers were real, then Gagne would have slightly more value to your team (all else being equal).

Tango, I'm not sure I agree with you (not saying you're wrong, just I dont follow your explanation) re: gagne/wagner. IMO wagner's (and other closers in between first and last) value makes a big difference.

say you are deciding between gagne(70 in your example) and vlad(150 in your example)...
lets assume if you draft one you can't get the other.

if wagner is worth 69
draft vlad - 150
draft wagner - 69
total 219
--
if wagner is worth 30
draft vlad - 150
draft wagner - 30
total 180
OR
draft gagne - 70
draft next best OF - 140
total 210

wagner's value matters. if gagne, wagner, and smoltz are all around 70, gagne's relative value decreases, regardless of the value of the last player drafted, because if you don't get gagne, you can still get a 70 point closer. but if gagne is 70 and the next best is 40, gagne is more valuable, because there's no other way to get 70 from a closer. it's probably going to be hard to get 70 from two closers!

FANTASY CENTRAL (February 21, 2004)

Posted 8:17 p.m., March 15, 2004 (#130) - Nod Narb
  my last paragraph:

wagner's value matters. if gagne, wagner, and smoltz are all around 70, gagne's relative value decreases, regardless of the value of the last player drafted, because if you don't get gagne, you can still get a 70 point closer. but if gagne is 70 and the next best is 40, gagne is more valuable, because there's no other way to get 70 from a closer. it's probably going to be hard to get 70 from two closers!

it does matter.

FANTASY CENTRAL (February 21, 2004)

Posted 12:00 a.m., March 16, 2004 (#134) - Nod Narb
  Take the following example of players and values. I tried to make this realistic. There are 5 1B who are very good and pretty close in value. There are 2 3B who are very good and pretty close in value.
However, the distribution of 1B falls of in value gradually, while the rest of the 3B fall off precipitously.
The 5 best 1B are probably better than the top 2 3B.

Helton(12), Thome(11.5), Giambi(11), Delgado(10.5), Bagwell(10), 6, 5, 4, 3, 1.5.

Chavez(9), Rolen(8), 4, 3.5, 3, 3, 2, 2, 1, 1

Tango and Sky would advocate taking Helton first, Michael and I would advocate taking Chavez first.

My rationale here would be that if you took Chavez (or Rolen), you still might be able to get one of the top 1B with your 2nd pick. Even if you didn't, you'd still be able to get someone at 5 or 6. But if you took Helton first, chances are much less that Chavez or Rolen will be left for your second pick, and you'd have to settle for someone at 4 or less.
The probability of getting 2 good players is higher when selecting Chavez (or Rolen) first.

FANTASY CENTRAL (February 21, 2004)

Posted 12:02 a.m., March 16, 2004 (#135) - Nod Narb
  btw, Michael - we'll probably be able to predict each others' picks with 90% accuracy on sat ;)

FANTASY CENTRAL (February 21, 2004)

Posted 1:07 p.m., March 16, 2004 (#138) - Nod Narb
  True. It is really hard to come up with a convincing, realistic example. I haven't the slightest on how to run a Monte Carlo, but it would be interesting to see the results.

FANTASY CENTRAL (February 21, 2004)

Posted 10:32 a.m., March 20, 2004 (#146) - Nod Narb
  We've had a few people drop out of the primer fantasy league, which drafts tonight. If anyone else wants to join, here are the details:

http://baseball.fantasysports.yahoo.com/b1
league ID: 2686
password: primer

draft is at 5:30 EST tonight

FANTASY CENTRAL (February 21, 2004)

Posted 9:09 p.m., March 21, 2004 (#148) - Nod Narb
  Tango - any chance of getting the Marcels for pitchers sometime soon? I'd be glad to help if you're too busy with other things.

Baseball Prospectus - : Evaluating Defense (March 1, 2004)

Posted 7:11 a.m., March 2, 2004 (#3) - Nod Narb
  Larry,

There's a link to the primate studies index right at the top of the Primate studies page. That should give you easy access to most things referenced in individual threads.

More Help Requested (March 4, 2004)

Posted 8:44 p.m., March 4, 2004 (#1) - Nod Narb
  When I worked in a cognitive psych lab investigating reaction time to visual stimuli, we had a program that automatically discarded all responses that were >3 SD from the mean. Maybe you'll want to parse out data in the same way. As long as your sample size is big enough for a given player.

The 2004 Marcels (March 10, 2004)

Posted 10:09 a.m., March 12, 2004 (#19) - Nod Narb
  5 - Determine an age adjustment. Age = 2004 - yearofbirth. If over 29, AgeAdj = (age - 29) * .003. If under 29, AgeAdj = (age - 29) * .006. Apply this age adjustment to the result of #4.

Am I reading this right? Those over 29 are expected to improve and those under 29 are expected to decline? Shouldn't it be (29 - age)?

Silver: The Science of Forecasting (March 12, 2004)

Posted 11:30 a.m., March 12, 2004 (#2) - Nod Narb
  How useful are similarity scores in predicting future development? Has anyone ever studied this exclusively? It seems to me that with advances in technology, training, nutrition, and [cough] supplements, there isn't much usefulness in comparing a modern day player to a player who played 30, 40, 50 years ago. At least to predict development.

I don't have BP 2004 with me, so I don't remember which 10(?) criteria they use for the basis of their comparisons. I know walk rate, K rate, etc. are included, so maybe I am way off - maybe these types of indicators transcend era. Thoughts?

Silver: The Science of Forecasting (March 12, 2004)

Posted 5:41 p.m., March 12, 2004 (#9) - Nod Narb (homepage)
  Ron Shandler also has an article about forecasting (see homepage)