i'm not asking, "do platoon splits make sense?" or "do some left-handed pitchers make sense as specialists in pitching to left-handed batters?" both of those things are obviously true. platoon splits are real. some LHP are real specialists.
what i'm wondering is if tony la russa, and major league baseball in general, is too focused on lefty-lefty matchups. are teams giving up more value by pulling right-handed pitchers out of games than they would lose by leaving them in? would the roster spots reserved for a couple of left-handed pitchers bring the team more value than if they reserved the spots for other players? or worse, are teams actually replacing better pitchers in that given situation with worse pitchers for that situation, just because the pitcher in question is left-handed?
it's not hard to tell that i'm thinking hard about arthur rhodes, and his numerous (mostly tragic) outings against left-handed hitters for the cardinals. specifically, rhodes was brought in to pitch to michael bourn, and gave up a lead-extending triple to him, one which extended the game. the cardinals were lucky enough to overcome the set-back.
it's bigger than rhodes, though. bigger, even, than tony la russa, i believe.
take a look below at the stats for this season's cardinal relievers against left-handed batters.
v. LHB (2011)
fernando salas - 3.84 FIP/3.76 xFIP [career: 4.49 FIP/3.89xFIP]
kyle mcclellan - 4.13 FIP/4.11 xFIP [career: 3.95 FIP/4.20xFIP]
jason motte - 2.35 FIP/3.73 xFIP [career: 4.07 FIP/4.23 xFIP]
octavio dotel - 6.85 FIP/5.04 xFIP [career: 4.81 FIP/4.71 xFIP]
marc rzepczynski - 2.63 FIP/2.50 xFIP [career: 2.90 FIP/2.92 xFIP]
mitchell boggs - 4.15 FIP/4.44 xFIP [career: 5.56 FIP/5.52 xFIP]
arthur rhodes - 7.36 FIP/5.41 xFIP [career: 2.94 FIP/3.12 xFIP]
lance lynn - 4.05 FIP/3.27 xFIP
eduardo sanchez - 2.93 FIP/4.11 xFIP
ordinarily, i would look only at the career numbers for relievers, since the tiny sample size in even a full season of relieving is fantasticaly unreliable, especially when pared further for platoon splits. the recent downfall of rhodes, though, makes it irresistable to cite the 2011 stats. in fairness to rhodes, while he's been terrible this year, he has had consistently good performance up until this season, posting neither an FIP or xFIP over 4.00 since 2004. still, his age combined with the radical drop in his numbers strongly suggests that this decline is part of the natural aging process, rather than a massive bout of misfortune.
the overall picture painted by the stats is that there's a real, if not enormous, advantage to pitching a left-hander against a left-handed batter. rzepczynski (and pre-2011 rhodes) poses a measurable advantage over a typical right hander - maybe a run or so over 9 innings against lefties. compared to more platoon-challenged ROOGY's like boggs or dotel, a good left-hander might be worth two runs or more in those nine innings. so, a very rough, back of the envelope calculation shows that a decent LOOGY might save you 3-6 runs over a season, since a typical true specialist would pitch fewer than 30 innings a year against lefties.
one should also not ignore the substantial downgrade in value LOOGY's will likely face when they are forced to face a RH batter - either because the LH batter they came in to face was pulled, or because there is one RH batter appearing between two LH batters. trever miller, for instance, has a career 4.87 FIP/5.17 xFIP against RH batters, which is terrible. he has faced 764 of them from 2003 to the present, even though he has only faced 907 LH batters, for a roughly 46%/54% split. managers are pretty terrible about adhering to the "specialist" part of the role. tony la russa is not the only, nor the most culpable, on this front. if anything, miller was more "specialized" with the cardinals. in his 2006 stint with the astros, for instance, miller faced 113 RH batters, and only 94 LH batters, which is not a specialist role at all.
in fairness, there's probably substantial selection bias here. if you put a true LOOGY in against skip schumaker, he'll likely be pulled for a pinch hitter. if you put a true LOOGY in against ryan howard or chase utley, the better hitter is more likely to stay in.
below are a sample of career splits among pitchers i have classified as LOOGY's. please note that this discussion does not address all-around excellent relievers who happen to be left-handed. billy wagner is a reliever and left-handed, but he's not a LOOGY.
JC Romero - career v. LHB: 3.44 FIP/3.57 xFIP
randy flores - career v. LHB: 4.22 FIP/4.23 xFIP
george sherrill - career v. LHB: 2.20 FIP/ 2.71 xFIP
joe beimel - career v. LHB: 3.68 FIP/4.18 xFIP
sergio escalona - career v. LHB: 4.56 FIP/ 4.59 xFIP
brian fuentes - career v. LHB: 2.82 FIP/ 3.30 xFIP
josh outman - career v. LHB: 1.98 FIP/ 2.82 xFIP
it was tough, in many ways, to try to sort out who truly was a LOOGY. and my criteria were not the most rigorous here. i looked for some classic names which are regularly trotted out when hunting for a bullpen left-hander. in some cases, i looked at how the pitcher was used - did he face more left-handed batters than right-handers? in some cases, i looked at how extreme the split was - is he merely average (or worse than average) in pitching to righties? that, in part, is the reason brian fuentes's name appears. he has a 4.15 FIP/4.37 xFIP against RHB. for his career. it's so strange to me that anyone would look at a pitcher who is pretty ordinary against more than half the batters out there as a closer rather than a specialist.
in excluding a lot of left-handed relievers from LOOGY-dom, what i found was that a lot of the teams out there -- especially the ones with good bullpens -- really didn't have specialists. those teams instead had left-handed pitchers, who were generally good pitchers from either side, even where they were better against LHB. those teams used their left-handers to pitch to both left- and right-handed batters. to me, this makes a lot more sense - think marc rzepczynski, not trever miller.
the other thing that was fairly remarkable was that a lot of "classic" LOOGY's are really not very good against LHB. joe beimel, for instance, has been mentioned every off-season as far back as i can recall as a LOOGY candidate. he's really a slightly above average pitcher to left handed batters. it's not clear that he's a meaningful improvement on a right-handed pitcher without a huge platoon split, like salas or mcclellan. similarly, trever miller has a 3.63 FIP/ 3.81 xFIP against lefties for his career. that's not shut-down pitching. that's a good but not great record against lefties.
what i would think of as a true LOOGY - ridiculously good against LHB, yet with no business pitching to RHB - was extremely rare. george sherrill (career FIP v. LHB: 2.20/ v. RHB: 5.17) and josh outman (career FIP v. LHB: 1.98/ v. RHB 4.64) were the only two which i found in my non-comprehensive review of left-handed relievers. outman - besides being a native st. louisan and having the best name ever for a reliever - has unfortunately not been used as a specialist, facing more righties than lefties. the remainder were either okay against RHB or failed to post outstanding numbers against LHB.
here are my thoughts on bullpen construction after all this.
thought 1: get the best relievers you can, whichever hand they pitch with.
- seven good right-handed relievers will be much better for your team than five good right-handed relievers and two terrible left-handed relievers, or even two left-handed relievers who are good at getting lefties out and not good at getting anyone else out. a left-hander good at getting everybody out is a significant advantage over a left-hander only good at getting 40% of the people out.
thought 2: make yourself aware of the platoon splits of your pitchers, and do not create a bullpen with too strong a split in either direction.
- as a caveat to thought 1, a bullpen full of octavio dotels and mitch boggs would be a weakness. extreme splits -- rather than mere left- or right-handedness -- do matter.
thought 3: if you take on a reliever with an extreme platoon split, make sure that you use him in a manner consistent with that platoon split.
- it was almost painful to review all these left-handed relievers who were affirmatively terrible against RHB, and see that many of them had pitched to more RHB than LHB.
it's very strange to me that, in a sport where tiny, arbitrary, meaningless split statistics are endlessly trumpeted and relied on (he's 4-for-9 against this pitcher for his career! he's 17-for-43 since june 7th! he's hitting 21-for-57 in afternoon games!) career-long platoon splits get ignored by the media, even by coaches and managers. at times, the only strategy that seems to have sunk in is that bullpens should have five right handers and two left handers, without much regard for whether either set of pitchers are good at getting same-handed or opposite-handed batters out. far too many terrible lefties are coasting on the mere fact of which hand they throw with.