At this point in 2010, many people considered the White Sox's rotation one of the top staffs in baseball. Lead by July acquisition Jake Peavy, they finally seemed to have the true ace they had lacked since Jose Contreras's dominant run in 2005. He was followed by Mark Buehrle, who could be penciled in to have another consistently good season. John Danks and Gavin Floyd followed, each of whom could be the number one starter on many teams. Freddy Garcia was set to finish out the rotation, and gave the Sox pitching to boot. This staff would wind up leading the MLB in WAR (according to Fangraphs), so it could be argued they DID have the best one in baseball.
Heading into this season, the Sox again look to have a top staff. Though not what the Phillies have, it could be argued they have the best staff in the AL. Though they again look to lack a true ace, they have one pitcher (John Danks) with an ace like mentality and two guys (Edwin Jackson, Gavin Floyd) with ace-type stuff. The fifth spot, however, is a bigger whole than it was last year.
John Danks, LHP: Danks took another huge stride last season, posting a WAR of 4.3 along with an ERA of 3.72. This put him among the top pitchers in all of the AL, and he looks to continue to grow. Heading into his 5th Major League season at only 26 years old, it would not surprise me if Danks takes a huge step forward to become a Cy Young candidate.
Gavin Floyd, RHP: Floyd started off last year as one of the worst pitchers in baseball, posting an ERA north of 6 for the first month of the season. From then on, however, he was arguably the best pitcher in the MLB. Floyd posted the exact same WAR as Danks, at 4.3, though he could have been so much more had he started off as even an average Major League pitcher. Until Floyd can put together a full season at a high level, he cannot be considered a great pitcher, but is still a VERY good second or third starter.
Mark Buehrle, LHP: What is there to write here? Buehrle had a down year in 2010, and still post a 4.28 ERA and a 3.8 WAR. He can be penciled in to have an ERA near 4 and eat a ton of innings, making him an extremely valuable 3rd starter.
Edwin Jackson, RHP: Jackson is not an ace. He is far to inconsistent to be considered that. But he is exactly what pitching coach Don Cooper has built his reputation on: a guy with impressive "stuff" but less success. We saw what he could be immediately after he was acquired for Daniel Hudson, and this would not be unreasonable to expect. This would not be an ace, but possibly the second best 4th starter in baseball (behind Cole Hamels).
The Fifth Starter: Their are few options here. Chris Sale has the largest upside of the group, which he showed with his domination out of the 'pen. If the Sox try to ease him into the rotation through the minors (which seems less and less likely) or keep in the bullpen, they have a gaping whole here. Tony Pena could fill in, but for more than a month, he could cause great negative value. Behind him is Lucas Harrell, who has almost no upside and would likely get exploited by any team that would face him. Luckily for the Sox, however, they have four workman starters, and this spot in the rotation could easily be skipped. I personally would like Sale in the rotation, and if he's ready, for the Sox to explore packaging Jackson or Floyd for a star hitter.
All in all, this staff will be one of the best in baseball providing the fifth starter is even replacement level. They have four VERY good starters (though no great ones), and a well rested Jake Peavy coming back (though no one knows how his lat will respond). If the offense is as good as it is supposed to be, the Sox could win a lot of games.