He used to frustrate the hell out of me when he was on the sox, but I think he will be a damn good pitcher this year.
His WHIP has only declined throughout his career, and even last year when he had a high ERA and lower strikeout ratio than in the past.
I saw him pitch some damn good games in while with Boston, including a few against NY where he just dominated their lineup. In fact, in his time with Boston he held the Yankees to .186 average and earned a scant .92 WHIP at Yankee Stadium. It was only at Fenway when he would give it up to their lineup, or anyone elses.
His road stats have always been surprisingly better. In 2004 for instance, 7 of his 10 wins came on the road where he posted a 3.06 ERA versus his 5.35 ERA at Fenway.
The other thing that he always seemed to have problems with was simply stamina. He would be great for 5 innings or so and then come back out to get shelled in the 6th. Again, at Fenway I think he had to throw a lot more pitches than in other parks.
He's a good pitcher who has a gift for movement and an explosive, oddly timed delivery that's hard to read, sort of like a more graceful K rod. Will he win the cy young? Obviously not, but he'll be a hell of a lot better than he was in the AL East.