I would put the Giants rotation 1. I am a Giants fan, so take it with a grain of salt, but they have the best blend of top tier talent (Lincecum, Cain), top notch veteran arm (Big Unit), and depth/upside at the back of the rotation (Sanchez, Zito, Lowry). I would put the Red Sox two probably because they are deep, and talented, the argument could be made for one. Beckett/Lester/Dice-K/Wakefield/Penny... Smoltz eventually, Buchholz I think will eventually crack the rotation as well not to mention some of the guys in the high minors and starter converted to reliever Justin Masterson if need be.
I don't particularly care for the Yankees rotation as much as others. Sure, C.C. Sabathia is a bona fide ace, no qualms there, but A.J. Burnett the two? Sure he has all the talent in the world, but it's funny how it only seems to show itself in contract years. Don't get me wrong, ace type stuff, but part of being a two is being able to take the hill every turn and throwing 200 ish innings, and I would bet he doesn't, I think it's more likely he throws under 150 innings then over 200. Wang is a solid 3, no argument, innings horse, but it is important to note the importance of a top notch defense behind a ground baller, and DJ is about the most overrated fielding SS in the game. The corners are manned by top notch fielders (A-Rod and Big Tex), but DJ is well below league average at SS, and to be honest I couldn't tell you how Cano rates. Still, Wang is a solid 3. Pettitte is garbage, lets be honest, his ERA and WHIP were nothing to write home about, and he's not getting any younger. Sure, he's a lefty, he'll eat up some innings, but will they really be quality? Joba has all the talent in the world as a 5, but the Yankees will likely have to closely monitor his innings, as I don't think he'll be able to throw more then 150. Another talented pitcher, very talented for that matter, like Burnett, but durability issues certainly come to mind, and I think he'll have some bumps in the road. Hughes is a nice 6th option, and teams could do worse then Kennedy/Mitre (when back from suspension) as emergency starters, but the fact is these are emergency starters who likely will have to be called on because of Burnett's propensity for getting hurt and Joba's innings needing to be held in check. Now after all that said, I do think they are a tier 2 pitching staff because they do have tons of talent, but I see them as 7-10, not top 5 material.
I also think the Brewers need to be moved up. Certainly the loss of Sheets and Sabathia will hurt, but as someone else pointed out Gallardo will likely make up for the loss of Sheets, and Parra should improve. I would imagine that rotation will be around league average, say 13-18 range. I love the Rays rotation and think that they are without question a top 5 rotation with Shields/Kazmir/Garza/Sonnanstine/Price and a solid swingman like Niemann. Overall interesting list, but I'd also have to throw the D'Backs in the tier 1 as well with two aces Webb/Haren followed by a high upside prospect in Scherzer and a veteran lefty Doug Davis and innings eater Jon Garland rounding out the staff and some high minor prospects not far off. Overall, interesting thread as it's surely starting debates.