Wednesday, August 13, 2008

For the sake of completeness

If you pay very close attention in the next few days, you will see why I am posting this. From 2005-2008, NL Position Players outside of Juan Pierre posted a .345 wOBA using the full formula from The Book. For various reasons, I am accustomed to using a simplified version that doesn't give credit for bases reached on error and that treats the HBP the same as an unintentional walk (wOBA gives a weight of .92 to ROE and .75 to HBP, meaning the simplification devalues the former by .539 runs and the latter by .026 runs if you assume an out value of -.3). Juan Pierre draws more HBP and ROE than the average hitter, so my simplification devalues him. By how much? From 2005-8, Pierre's wOBA is .3073 with the simplified formula against a league of .3359; with the full formula, it is .3195 against a league of .3451. So my simplified version makes him -16.1 per 650 PA instead of -14.5.

However, by "full formula" I am still referring to a formula that removes all IBB and SH. For a player with as many bunt attempts as Juan Pierre, that obviously works in his favor. If I include the SH in the PA term in the full formula, Pierre goes to -16.55. If I include IBB as walks, Pierre (who has only 2 in the period and 5 for his career) is -18.2 per 650 PA.

This isn't an anti-Pierre post, by the way, it's just a preemptive footnote. But I guess since I'm on the subject and Pierre started against Cole Hamels last night, I'll take a look at the idea that Pierre should be subbing for Andre Ethier. For his career, Ethier has a .318 wOBA (simplified as above) against LHP (299 PA) and .356 wOBA against RHP (1072 PA, and at this point, he's had extremely similar numbers against RHP in each season in case you were curious). Pierre is .314 (1462) against LHP and .324 against RHP (4117). But using the unsimplified formula, Pierre's gap shrinks to only 5 points of wOBA when including ROE, whether or not any of the SH and IBB are added. So there is something to the idea that Pierre is about as good against LHP as against RHP, and interestingly it is in part because Pierre has a higher ROE rate against LHP and a much higher HBP rate (30 of his 59 career HBP came against southpaws). Of more significance is that Pierre has struck out slightly less against LHP; from 2005-8, LHB have struck out in 21.9% of PA against LHP and only in 16.1% of PA against RHP. Meanwhile, if you include everything including the IBB, Ethier has a .365 to .332 gap, which is pretty similar to the league-wide (05-08) gap of .348 against .311. Now, the league-wide number has sample bias issues so let us not confuse it with the notion of a typical split for an individual player. In any event, though, Ethier's splits thus far indicate he's about typical in his split (despite having a higher BABIP in his 299 PA against LHP). In a league of a .331 wOBA, we would expect Ethier to be about .320-.325 against LHP and .350-.355 against RHP. Pierre is perhaps more like .310 against RHP and .300-.305 against LHP. So if you believe the gap between the two in Fielding+Baserunning is about 12 runs in favor of Pierre (say, +14 runs in range for Pierre, +7 in arm for Ethier, and +5 in baserunning for Pierre) then it would indeed mean Pierre has a one run advantage against LHP and a 13 run disadvantage against RHP (over a full season, that is).

(Obviously, you don't do it based just on the relatively small sample of their actual platoon splits, since you need to regress. But we have no reason to believe Pierre's split will be the typical because he is far from a typical player. We'd want to regress to a mean for left-handed hitters with a similar offensive game, not LHB in general. It's something I've wanted to study for a while but have not yet done, so hopefully the approximation above is close enough.)

So if Torre wants to start Pierre against LHP instead of Ethier - which saves the much better hitter for PH duty against RHP relievers, just as was done last night - then I don't mind.

Now, you may be asking how I could make that argument when this very blog has several times argued that Pierre shouldn't be starting against LHP. I still believe that Pierre the player is not somebody you want starting against LHP, and it all comes back to opportunity cost. Simply put, it is easy to get a good RHB outfielder to cover the days that LHP are starting. Mr. Colletti seems to either entirely not grasp this concept or to be vehemently opposed to it, as in his first year he jettisoned three of the four candidates in the Dodgers' system (Jayson Werth, Cody Ross, and Justin Ruggiano), even though the former two are arguably good enough to play everyday and the one he kept, Jason Repko, has never been much of a hitter. The Dodgers' outfield starters in Colletti's tenure have included lefties Drew, Lofton, Ethier, Pierre, and Gonzalez with no RHB getting serious time on the bench other than Kemp, Repko, and Brady Clark's 66 PA (switch-hitters Delwyn Young and Jose Cruz have also been 4th/5th OF for parts of a season). This season, Colletti signed RHB Jones and then replaced him with Ramirez, but that didn't address the issue since it has still fundamentally been Pierre and Ethier that are alternating playing time as the two RHB have been the better overall players (or, in the case of Jones, treated as if they were the better overall player). The Dodgers don't have a LHB who is truly above average on a day an LHP starts, and they haven't had one in Colletti's tenure other than perhaps Drew. But given the poorly-constructed roster, with Jones on the DL it is sensible to be starting Pierre against LHP.


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