Ah yes. The designated hitter. If you want a baseball argument guaranteed to devolve into a shouting match inside of five seconds, just say "DH" and run.
Just so you're aware, the DH is an evil evil thing. Bob Gibson wasn't above hitting. Walter Johnson wasn't above hitting. Satchel Paige wasn't above hitting, or Cy Young, or Sandy Koufax, or Lefty Grove, or Dizzy Dean. Three Finger Brown had to hit, and Three Finger Brown had three fingers.
And here's the other thing. Babe Ruth started as a pitcher. Had the DH been around back then...
...well, actually, had the DH been around back then, Ruth could still have hit. For you see, the designated hitter is an opt-in proposition. If the pitcher wants to hit, the pitcher can hit.
And, at least by American League rules, there is a potential stupid tax: you can lose the privilege of a DH.
*The DH cannot field; if you take out a field player and move the DH into that position, the DH is forfeit, and the pitcher must bat.
*If the DH chooses to pitch, for some reason, well, he's not a DH anymore; he's a pitcher who bats. And the pitcher must then bat.
*If a pinch-hitter comes in for some other position, and then goes in to pitch... he's now a pitcher who bats. Bye bye, DH.
*If the manager simply forgets to name a designated hitter? Well, that was stupid. Pay the stupid tax.
Also, there is no double-switching. That, for those not familiar, is when you replace two players at once and swap their corresponding positions' spots in the lineup- for example, if the catcher bats third and the shortstop eighth, and you replace them at the same time, you can end up having the shortstop bat third and the catcher eighth. You can't do that with a DH.
It doesn't happen often, though a DH forfeiture occurred on four occasions last season, including Game 3 of the ALCS, when DH Jerry Hairston Jr. replaced right-fielder Johnny Damon in the 10th inning. When Mariano Rivera's turn subsequently came up in the top of the 11th, he was pinch-hit for by Francisco Cervelli, who struck out. The Los Angeles Angels, no longer having to deal with Rivera, scored and won in the bottom of the 11th. Alfredo Aceves, who gave up the run, got the loss.
Of course, this is something the Yankees should have already had to deal with: bat Rivera, or pinch-hit for him, lose him, and hand the ball to the dregs of the bullpen you didn't really want to send to the mound?