He didn't pitch poorly, but he didn't pitch all that great either. Four runs in five innings with only two strikeouts. Remember, this is a guy that had a 2.55 ERA before his last 1/3 of an inning before going on the DL. He looks like a spring training pitcher going against hitters with good timing. One more start may not be enough, as he only lasted 74 pitches last night.
He has to be calm and consistent, and have the ability to throw 100 pitches with confidence. Sure, he could come back right now, but with the recent five-game losing streak, the Tigers need pitchers who they can get behind and fee confident they are going to win the game. They will have that in Maroth. It just might take a little more time.
If the Tigers sweep Boston, and win three of four against Texas, Maroth might only take one more minor league stint, and the Tigers should bring him back up to the big club before the White Sox series, maybe to use him out of the pen if someone has a rocky start against the team from the windy city. But there would be no pressure, as that would likely sew up at least the wild card. However, if they lose six straight, and are going to play Chicago--this time for the division--it will be hard not to bring him up to give him a start, ready or not. Leyland, however, is not in the game of rushing players back.
Toledo, on the other hand, only has a dozen or so games left, and they are in a pennant race, only 2 1/2 games back. Maroth, at most, can get two starts before the playoffs hit, so they might want to just wait until September to bring him back. Plus, it will give him the added pressure of pitching in a race, even if it is in the minor leagues. That's the same reason Cameron Maybin has been stuck in A ball this entire season.
Regardless of when Maroth comes back, he will join the rotation eventually, Miner will drop to the pen, and when the playoffs hit, he will get his starts assuming he doesn't totally implode. The most important thing to remember is that he is still relatively young, and it's better to have him sit than have him pitch poorly because he is not ready. He already is a 21 game loser at the Major League level. He is still learning how to win.
But with the game on the line, there aren't many more Tigers I'd want to have out there...
