the release this week of JC Romero prompted me to think harder about an issue that has long perplexed me - why major league baseball continues to endorse the role of the LOOGy far in excess of what could possibly make sense.
just as a usage note, all left-handed relievers are not LOOGys. the very concept of a "left-handed one out guy" is a left-hander whose primary purpose is to see a single left-handed batter and then leave. that naturally entails being merely mediocre against right-handed batters. sean marshall is not a LOOGy. marc rzepczynski is not a LOOGy.
the whole premise of the LOOGy is that a left-handed reliever can be relegated to facing left-handed batters more or less exclusively. looking for a left-handed reliever who is good at getting left-handed batters is the sole aim; whether the pitcher can get right-handed batters is almost immaterial, under the theory.
but the sad reality of baseball is that such exclusivity is virtually impossible. for one, a manager properly using a LOOGy may still face the scenario of an opposing manager swapping in a RH pinch hitter. under the rules, barring an injury, a reliever must face at least one batter once he enters a game.
other scenarios will arise where a LOOGy must face RH batters. when games reach into the late innings, all hands must be on deck; the alternative may be having shortstop pitch. when, as happened last week, the starting rotation turns in short starts, and the bullpen wears thin, the LOOGy must pitch.
and this happens far more than the theory of the LOOGy would suggest.
i sorted all MLB pitchers, eliminated those with at least one start and those who had faced 45 or fewer batters. among that reliever corps of 252 pitchers, one pitcher had faced 76% LHB out of all the batters faced, the Orioles' Clay Rapada. only 51 of these relievers faced at least 50% LHB in their total batters faced. only 9 such pitchers faced at least 60% LHB.
that is a surprising outcome. if an ordinary left-handed specialist can reasonably be expected to face 40% RHB, no one can dismiss how badly a LOOGy pitches to a RHB.
the only way a LOOGy can be valuable is if he is actually not terrible against RHB - in which case he verges on not being a true LOOGy - or if he is so outstanding in facing LHB that his outstanding performance v. LHB outweighs his miserable performance against RHB.
here's a list of the 15 relievers who had the largest gap between their overall xFIP and their xFIP against LHB. what constitutes a LOOGy is somewhat subjective, so i used that disparity as the basis for selecting the group. note that there may be some anomalies in the group. kevin jepsen, for instance, is not left-handed at all and has career numbers showing better performance against RHB.
and in that list, we see some of the serious problems with the LOOGY theory. only three of the 15 pitchers faced more than 60% lefties. six of the 15 pitchers faced more RHB than LHB. some of that disparity is probably poor managing; surely charlie manuel is an accomplice in making JC Romero face almost two RHB for every left-handed batter.
managerial influence seems fairly weak; a LOOGy can really range between about 45% and 60% LHB. however, that usage may be somewhat important. notably, all but one LOOGy listed above who saw less than 50% LHB was sub-replacement value. all but one of the LOOGys listed above who faced more than 50% LHB were over replacement value. that may be reading far too much into small amounts of information; we're really talking about a tiny number of runs above replacement among a small number of pitchers.
still, it seems uncontroversial that a pitcher with a severe platoon split should face at least 50% batters whom his split favors.
perhaps more surprising - and more damaging to the LOOGy theory - is that this group of pitchers is, on balance, a tick below replacement value. there are plenty of good left-handed relievers who are excellent; there are precious few LOOGys who provide significant value year after year.
among the best relievers against LHB from 2008-11 by FIP v. LHB, only george sherrill and randy choate could be called LOOGys. choate was worth a whopping 0.8 WAR over that time; not as a per year average, but as a total over 3 seasons. sherrill was worth a total of 1.4 WAR in those three seasons.
the only real argument in favor of the LOOGy is that the LOOGy will pitch his highest leverage appearances against LHB and his lowest leverage appearances against RHB (e.g., mop-up duty, blowouts, etc.). if that is the case, then WAR may not be the best measure of reliever performance in this case. who cares if your LOOGy gives up a bunch of runs pitching the 7th inning in a 15 to 1 blowout, as long as he shuts down the big lefthander in a one-run game?
there is a gap in the data; no one that i can see provides leverage splits relative to handedness of a batter. but i question whether it is likely that any data would support such a conclusion.
first, the sheer number of appearances against RHB - other than those rare or well-managed or lucky LOOGys pitching 70% of the time to LHB - indicates that a strong leverage split is unlikely.
second, several of the scenarios in which a LOOGy would pitch to a RHB are not likely to be low leverage. first, a LOOGy who must pitch to a RH-PH called in to replace a LHB will almost certainly be in that high-leverage circumstance in which he would face LHB. second, pitching in extra-innings games will surely be high-leverage, since the game will almost certainly be tied (unless he enters mid-inning). third, while not technically fitting the "one-out" part of LOOGy, many managers will use a LOOGy to face a pair of LHB sandwiched around a RHB in a high leverage situtation. these are all examples of high-leverage scenarios where a LOOGy will likely face a RHB.
i continue to find it difficult to identify anyone other than george sherrill currently playing who really fits the definition of LOOGy and provides more than marginal value over replacement season after season. when choosing which reliever should face a particular batter, field managers should pay attention to handedness and platoon splits. when choosing which reliever should fit on a roster, general managers should basically ignore handedness and pick the best reliever available relative to their resources and other needs.
until someone shows a serious benefit to LOOGys, it shouldn't matter whether a team has 4 left-handed relievers or none. the idea that a club needs a left-handed reliever is merely keeping a lot of bad pitchers employed.
and, should clubs ignore the above advice, field managers should at least make sure that they use any pitcher with an extreme split appropriately; using a specialist to face less than 50% batters favored by his split is just hurting one's club.