If Pettitte is a fifth starter, he is without question the best fifth starter in baseball right now, given that he would be a #3 in most other teams in the game and perhaps even a #2. Put him on some of the lesser-quality teams like the Nationals, Rockies, and Pirates and he might actually be the ace.
If the Yankees have a fifth starter, it sure isn’t Andy Pettitte, and if any of their starters is going to be relegated into bullpen duty, it should not be Andy Pettitte. People really need to start realizing that what he brings to the table is not a marginal upgrade over an average or replacement pitcher but rather almost the guarantee of +3.5 to +4 wins.
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FanGraphs: Why No Love for Pettitte?
Eric Seidman makes the case that Andy Pettitte should not be getting the Joba argument. I did not realize at all that he's already been worth a full win by FG WAR this season and has pretty much been an All-Star caliber player the last several seasons.
Frankly, I just assumed there was merit to him being the 5th starter and a bullpen option. Guess I was wrong.