You can make a case that he pitched well before he joined the Yankees as well as after. 2002 was his first full season in the big leagues and with Montreal and Florida, he was 6-10, 5.16, 136 IP in 37 games, 22 starts. In 2003, he was 12-13, 4.30, 201 IP in 32 starts. After 2004 got him the contract, his post Yankees career started in 2009, going 14-12, 5.10, 199 1/3 in 33 starts for Cleveland and Minnesota. 2010 earned him an extension, going 17-11, 3.75, 221 in 32 starts. Last year he was 9-13, 4.30, 222 in 33 starts for the Twins.
I look at it this way. Pavano was never the pitcher the Yankees expected him to be. Remember, the Red Sox traded him to the Expos for Pedro Martinez! He never measured up to the prospect hype he got when he was in Boston. If you put his 2009 or even 2011 stats on the Yankees, he would be run out of town just as quickly as AJ Burnett is right now.
The combination of his prospect hype and his 2004 season got him his contract, but sometimes a pitcher is just not that good. There is no doubt he is a serviceable pitcher, but he is no better than a .500 guy who makes 33 starts and pitches 200 innings a season. And baseball needs pitchers like that. More than likely, he will pitch a couple more seasons after his contract runs out after 2012. The Twins may pick up his 2013 option or he may pitch 2 or 3 seasons in a place like Seattle or San Diego. I'd be surprised if he pitched for a big market team again.