You can look at ST numbers if you'd like, I prefer not to because they're extremely deceiving (See: Toronto Blue Jays).
But if you want to - the Red Sox have a 3.90 ERA this spring. The Rays have a 4.46 ERA, and the Yankees have a 3.72.
For the Sox, Beckett has a 0.95 ERA, Lester a 3.50 (but was nothing short of outstanding in his last outing), Buchholz a 4.80, Doubront a 2.70, and youv'e cited Ace and Bard.
For the Yanks, CC has a 4.50 ERA, Pineda a 3.31 (albeit with lower velocity), Nova a 6.86, Kuroda a 2.91, Hughes a 2.03, and Garcia a 2.92.
For the Rays, Sheilds 2.04, Price 3.79, Moore 9.00, Hellickson 10.13, Niemman 4.05.
If you're just looking at those numbers, the Sox have the 2nd best rotation, well above the Rays, and have a much, much better offense.
But, the Blue Jays have a 2.60 team ERA, which is why I don't read into these numbers, both for team and individual.