In this age of the 12-man bullpen, Major League Baseball teams scour the ends of the earth trying to find relievers who are capable of getting anyone out. One of the most coveted relievers is the left-handed specialist who can enter a late-game situation and get the big-bopping lefty out. 

Just look back to the trade deadline and see some of the players traded. Cleveland acquired Marc Rzepczynski from St. Louis; Atlanta took Scott Downs from Los Angeles; Boston grabbed Matt Thornton from Chicago. 

Three potential playoff teams made a point to go after left-handed relievers whose only valuable skill is an ability to get left-handed hitters out. That’s not an exaggeration, either. Take a look at the OPS against for Rzepczynski, Downs and Thornton versus lefties and compare it to righties this season:

With more and more teams investing roster spots and seven-figure salaries in these kinds of players, is it worth it?

The role of the bullpen and use of relief pitchers has changed so much over the years that it was just a matter of time before things got so diluted that teams were forced to take on one-dimensional arms just to keep up with the changing times. 

In a 2004 article by Rany Jazayerli of Baseball Prospectus that examined the history of pitcher usage, the average innings pitched for a league leader last decade dropped more than eight percent from the 1980s. 

The emergence of full-time relief pitchers in the 50s and 60s gave teams the luxury of using their starting pitchers without having to account for the possibility of an emergency relief outing. Freed to focus their starters’ usage solely as starting pitchers, teams were able to plan their starting pitchers days and weeks in advance–and the pitching rotation was born.

What teams want from a specialist is not that different than what they want from their traditional setup man. I should clarify how I define “traditional setup man.” I believe it to be a primary relief pitcher used in high-leverage spots late in games (typically seventh- and eighth-inning guys). 

The best example of a “traditional setup man” pitching today is David Robertson of the New York Yankees. He isn’t going to pitch in the ninth inning as long as Mariano Rivera is there—just one more month!—but Joe Girardi doesn’t hesitate to use him in a big spot, usually in the eighth inning but occasionally giving him some work in the seventh. 

Robertson is a pitcher who has proven adept at getting both righties and lefties out. He does have a slight reverse platoon split with right-handed hitters posting a .227/.284/.352 line against .159/.231/.215 for left-handed hitters. 

Using just Robertson as an example in this case, it is clear that the Yankees get far more value from him than they would if they were limited to a left-handed specialist. Rzepczynski is the only specialist among the three we listed with a lower OPS against lefties than Robertson. 

Now, Robertson is an extreme example because he is one of the best relievers of any kind in baseball, so in order to provide a better representation of the question we are asking, we have broken down the performance of the top 15 traditional relief pitchers based on WAR and compared their respective opponents’ OPS to the top 15 “lefty specialists” last year. 

As you can see, things get very interesting when you start to break them down on a deeper level. Not only are the traditional relievers posting a significantly lower OPS against right-handed hitters, but the total was also lower against left-handed hitting. 

That isn’t to say there is no value in having a pitcher whose specialty is getting left-handed hitters out, but it is in a team’s best interest to always look for a pitcher who can do more than just one thing. 

To me, lefty specialists are a lot like a great defensive player who can’t hit: They are valuable additions near the back end of a roster, but they’re not players you want to carry if you can help it. 

I mean, in the scheme of things, how often are managers going to rely on a left-handed specialist? We are talking about one out in a game. Granted, that particular out could go a long way towards deciding the outcome, but over the course of 162 games, the overall impact is maybe 0.5 wins above replacement. 

But the reason that you will find so many lefty specialists around baseball—seriously, look at every roster right now and you can probably find at least one per team—is because there aren’t enough of traditional setup relievers to go around. 

The rate of attrition in bullpen arms is incredible. The only teams to have the same closer in 2013 as they did in 2010 are the Yankees (Mariano Rivera) and Indians (Chris Perez) because it is hard to keep relievers healthy. With the price tag for closers skyrocketing, no one wants to pay that much money for Proven Closers. 

Even though traditional setup men are much, much more valuable to teams because of the flexibility they provide, most notably for the extra roster spots, the specialists aren’t going to go away because teams will always need more relief pitching. 


Note: Stats courtesy of and unless otherwise noted. If you want to talk baseball, feel free to hit me up on Twitter with questions or comments. 

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