I'm a big believer in Pythagorean record as a test a team's quality.  I like the simplicity: reduce runs allowed or increase runs scored to increase winning.  Hitting, pitching and defense are already built into the analysis.  (Click here for a down and dirty explanation).

I was surprised to find that 2009 was not a marked improvement over the previous 3 clubs.  The pitching and defense was actually worse than the 2008 squad, and whole team was roughly equal in 2006 and 2009.

Could it be that the big transformation wasn't CC or AJ or Hughes in the pen. Certainly, both players were essential to replacing Mussina, to cover for the loss of Wang, the 5th starter debacle and a slight regression by the bullpen (87 OPS+ against in 2008; 92 in 2009).  But those problems at the back of the rotation mask the improvements at the top..  It was the addition of Tex and the return of a healthy Posada and Matsui that really put the team back in the driver's seat.

On the other hand, the Yankees significantly overshot their expectations in 2009, so unless the team improves on one side of the ball or the other, we had better brace for a step back in 2010. 

Having Mariano in the pen (and a strong pen in general) seems to skew the Yanks to the top side of the projections (because they lose fewer close games than other teams). While I expect Joba/ Hughes/ mystery pitcher to outperform 2009 Joba/ Wang/ Mitre/ Gaudin, I'm worried that will be balanced by a step back for CC or AJ.

Johnny Damon was a decent offensive left fielder but a terrible defensive one.  Offensively he was 24.5 weighted Runs Above Average, and defensively -9.2 runs below average according to UZR, for a net of +15.3 runs.  Matt Holliday netted +39.6 runs in 2009.  Jason Bay netted +23.0.  My preference, Mike Cameron, netted +18.8 as a centerfielder.