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OPS: Begone! Part 2

May 30, 2003 - Peter Keating (e-mail)

I appreciate the utility of Base Runs and Linear Weights, but I'm wondering if some of the examples Tango has used run into the apples-and-oranges problem in using OBP and SLG, namely that they have different denominators.

In the Clutch Hits thread that originated with the Thomas Boswell article on how sabermetric principles are taking hold in MLB, someone asked whether, given the same on-base average and slugging percentage, a higher batting average is more valuable. After some back-and-forth, a couple of posters wrote that BA doesn't matter; if Player A has a lower BA than Player B but an equivalent OBA and SLG, then he must be compensating with more walks and isolated power.

Tango gives a different answer here: he says that if we hold OBA, SLG and the number of outs constant, reducing BA increases run generation, as measured by Base Runs or Linear Weights, in a small but noticeable way.

But this is the opposite of what Runs Created says, and even though Tango has deconstructed RC, I think the discrepancy tells us something.

Suppose Player 1 bats .250, with a .400 OBA and .500 SLG. In 600 plate appearances, or 360 outs, he will create 96 runs by the basic RC method:

120 hits in 480 AB, with 30 2B, 30 HR, 120 W = 240 times on base, 240 total bases, 600 PA = 96 RC

Now suppose Player 2 has the same OBA and SLG in the same number of plate appearances and outs, but hits .350. He will create about 111 runs:

194 hits in 554 AB, with 23 2B, 20 HR, 46 W = 240 times on base, 277 total bases, 600 PA = 110.8 RC

What happens when we hold outs and OBA constant is that 'times on base' also has to stay constant. But because Player 2 has a higher batting average, he will walk less frequently and have more at-bats, more hits and more total bases than Player 1. And because the players have identical slugging percentages, Player 2 will add total bases at a rate proportional to the *at-bats* he is adding, not to his plate appearances or his outs. And that means his RC and RC/out will go up.

Note that Player 1 and Player 2 both create 0.2 runs per AB. But Player 2 is creating about 15% more runs than Player 1 on a raw or per-out basis. This is because RC = times on base x total bases / plate appearances, and has nothing to do with at-bats, while SLG takes AB as its denominator.

In other words, if we wanted Player 2 to maintain the same number of RC per out as Player 1 while increasing his BA, it's not SLG we should be holding constant, but 'advancement percentage,' or whatever you want to call total bases / plate appearances.

To see why this is more than a technical argument about Runs Created, look at Tango's final table.

The bottom-line player (the guy who hits .185) is on base 220 times (100 hits, 120 walks), has 221.4 total bases (100 hits, 30 2B, 4 3B, 27.8 HR), and uses 440 outs in 660 plate appearances.

Using the same 440 outs in the same 660 PA, the top-line player (who hits .313) is on base 220 times (200 hits, 20 walks) and has 262.3 total bases (200 hits, 30 2B, 4 3B, 8.1 HR). Yet he is creating 2.6 fewer runs than the first player according to Base Runs, and 4.4 fewer according to linear weights.

My questions are:

1) How can injecting more than 40 extra bases into the same number of plate appearances or outs produce a negative result?

2) How can Base Runs and Linear Weights work if that's what they do?


OPS: Begone! Part 2

May 30, 2003 - Peter Keating

'40 extra bases on hits, but 100 less bases on walks'

I'm not sure I understand this. In moving from the bottom guy to the top guy, we're not taking away 100 walks and adding 40 singles. We're taking away 100 walks, adding 100 hits and making sure that the 100 hits are configured so that the second player winds up with 40 more total bases, right?


OPS: Begone! Part 2

May 30, 2003 - Peter Keating (e-mail)

So then comparing them by looking at times on base and total bases points up a problem with Runs Created, rather than some problem with using OBP and SLG in combination even though they are denominated differently?


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