Many fans go crazy over the usage of "lefty-specialists" in baseball. This is how pitchers like Mike Stanton and Mike Myers stuck around baseball for so long. While they were great pitchers, they were often used to get certain left handed hitters out and then taken out of the game.
So lets look at certain pitchers in the game today and determine: Do matchups (righty vs. righty lefty vs. lefty etc) mean as much as people think they do?
.222 vs. left
.219 vs. right
Yes, the numbers are better vs. righty hitters. The Yankees do use Coke as a lefty specialist sometimes, but also use him as a set-up man.
.250 vs. left
.161 vs. right
J.P. Howell is not exactly a specialist for the Rays this year, as he has done long-relief and even some closing. Still, the numbers are startling.
.275 vs. left
.227 vs. right
Yes, Scott Downs is a closer on the DL currently, but he has been used before to get lefties out. The numbers once again show that he has an easier time when there is a so-called "mis-match."
Now lets look at some Yankees pitchers from the right-side. Are they better against the righties or the lefties?
.242 vs. right
.207 vs. left
Aceves is a long-reliever and has been lights out against teams not named Chicago. The stats show he is doing better in mis-match situations.
.324 vs. right
.205 vs. left
Bruney has been, well, horrible this season. After a semi-strong start he has absolutely faltered out of the pen. The numbers say he has still been very good against lefties, though.
.230 vs. right
.170 vs. left
Robertson has been used mostly in the wipe-up or 7th inning roles.
Of course, however you can make the opposite argument, that lefty-specialists DO work out, if you use the right ones.
.159 vs. left
.288 vs. right
.176 vs. left
.255 vs. right
I ask you, though: Bases loaded two-outs 7th inning your team is up 1 run. Would you rather have a lefty-specialist in, or your power set-up man?