But here's an alphabetical-order look at what currently looks like the 10 best rotation foursomes in baseball.
Angels: Weaver, Haren, Wilson and Santana
Combined 2012 salary: $47.5 million
Combined 2011 stats: 61-37, 2.97 ERA (306 ER/926 IP), 3.29 K/BB ratio (774 K/235 BB)
Even without Wilson, the Angels' rotation ranked second in the American League in 2011 -- behind only the Rays -- with a 3.59 ERA. With Wilson, they have yet another frontline starter, good balance with a left-hander joining the fold and the look of the top staff in the Junior Circuit. This calendar year, the Angels got a steal for Weaver by signing the Scott Boras client to a five-year, $85 million contract before he could hit free agency. The Halos then took Wilson away from the AL West-rival Rangers to likely slot him behind Haren. Behind Wilson, is there a better fourth starter in baseball than Santana?
Braves: Jurrjens, Tim Hudson, Tommy Hanson and Brandon Beachy
Combined 2012 salary: $15.1 million
Combined 2011 stats: 47-26, 3.34 ERA (237 ER/638 2/3 IP), 2.91 K/BB (559 K/192 BB)
A lot can change if Jurrjens is traded, and his name has certainly been out there. But with young arms like Mike Minor, Randall Delgado and Julio Teheran also in the fold, the loss of Jurrjens may not even change the fact that the Braves have one of the best rotations in baseball. Still, there is plenty of risk involved with dealing Jurrjens, who looked like a National League Cy Young Award contender before a right knee injury forced him to miss the final month of the season. Hudson isn't getting any younger, Hanson is recovering from a right shoulder injury and everyone else is awfully young and unproven.
Brewers: Yovani Gallardo, Zack Greinke, Shaun Marcum and Randy Wolf
Combined 2012 salary: $35.3 million
Combined 2011 stats: 59-33, 3.64 ERA (320 ER/792 IP), 3.08 K/BB ratio (700 SO/227 BB)
The Brewers stripped almost their entire farm system to land Greinke and Marcum last offseason. They then finished the ensuing regular season 10th in the Majors in starters' ERA. Now, heading into 2012, their deep rotation faces some questions. Will Greinke, owner of a combined 4.02 ERA the last two seasons, ever return to his AL Cy Young form of '09? Was Marcum simply gassed while giving up 34 runs in 34 innings through his last seven starts of the season (including the playoffs)? And is Gallardo a legit staff ace? Questions aside, though, there's no denying that the Brewers are at least solid from top to bottom.
Cardinals: Chris Carpenter, Adam Wainwright, Kyle Lohse and Jaime Garcia
Combined 2012 salary: $34.625 million
Combined 2011 stats (using Wainwright's 2010 numbers): 58-35, 3.18 ERA (301 ER/850 2/3 IP), 3.31 K/BB (671 K/203 BB)
Yeah, the Cardinals lost Albert Pujols to the Angels, but don't forget: They won the World Series without their No. 2 starter. Now, Wainwright is expected to head into Spring Training healthy after undergoing Tommy John surgery, giving the Redbirds the equivalent of a high-profile offseason signing. If Wainwright can bounce back from the procedure as well as Carpenter did when he had the same surgery in 2007, the Cardinals will once again have two premier aces at the front of their rotation. As for Garcia? His numbers this past season weren't as spectacular as those of his rookie year, but his walk rate was way down. Lohse, meanwhile, made a case for NL Comeback Player of the Year.
Diamondbacks: Ian Kennedy, Daniel Hudson, Trevor Cahill and Joe Saunders
Combined 2012 salary: $13.2 million
Combined 2011 stats: 61-43, 3.54 ERA (340 ER/863 2/3 IP), 2.45 K/BB ratio (622 K/254 BB)
The D-backs proved they're in win-now mode on Friday, when they dealt their best pitching prospect (Jarrod Parker) to the Athletics for the proven Cahill. The young sinkerballer fell off a bit from a spectacular 2010 but still put up solid numbers -- 12 wins and a 4.16 ERA in 207 2/3 innings with the A's. Now, he'll be slotted behind two young studs in Kennedy and Hudson, who combined to win 37 games with a 3.18 ERA in 444 innings in 2011. Saunders remains either a trade or non-tender candidate, but 25-year-old righty Josh Collmenter (10 wins and a 3.38 ERA in 2011) is also more than capable as a back-end starter.
Giants: Tim Lincecum, Matt Cain, Madison Bumgarner and Ryan Vogelsong
Combined 2012 salary: $35.2 million
Combined 2011 stats: 51-45, 2.89 ERA (264 ER/823 2/3 IP), 2.85 K/BB ratio (729 K/256 BB)
The Giants' rotation has ranked among the top three in the Majors in ERA each of the last three seasons. With Lincecum and Cain at the top, and the upstart Bumgarner in the No. 3 spot, there's little reason to believe that shouldn't continue. Last year, the Giants' staff combined for a 3.28 ERA to trail only the Phillies in that category. The rotation even got some surprising contributions from Vogelsong, who went four years without pitching in the Majors but finished 13-7 with a 2.71 ERA. There must be something in the water in San Francisco.
Phillies: Roy Halladay, Cliff Lee, Cole Hamels and Vance Worley
Combined 2012 salary: $56 million
Combined 2011 stats: 61-26, 2.59 ERA (234 ER/814 IP), 4.62 K/BB ratio (771 K/167 BB)
They're the most well known, the most expensive and, until someone proves otherwise, the best. The Phillies' rotation led the Majors in basically every category last year - wins, ERA, complete games, innings, strikeouts and strikeout-to-walk ratio. They'll likely lose Oswalt this offseason, but it matters little with Halladay and Lee at the top -- two guys you can easily consider the two best in the NL -- and Hamels the No. 3 starter. The combined numbers for Halladay and Lee in 2011 are freakish: 36 wins, a 2.37 ERA, 458 strikeouts and 77 walks. Hamels would be a staff ace on many other teams, and Worley had a spectacular rookie season.
Rangers: Colby Lewis, Derek Holland, Matt Harrison and Alexi Ogando
Combined 2012 salary: $7.15 million
Combined 2011 stats: 57-32, 3.84 (321 ER/753 IP), 2.61 K/BB ratio (583 K/223 BB)
You might have noticed one obvious omission from this foursome: Neftali Feliz. The 23-year-old right-hander and former closer will be transitioning to the rotation in 2012 -- a move that may have set up the Angels to outbid the Rangers for Wilson's services. If there's a team you can count on to bounce back from the scenario this club faces, it's the Rangers. They've successfully converted Wilson and Ogando from relief roles to the rotation in the past. And one year after losing Lee to the Phillies, their rotation put up better numbers.
Rays: David Price, Shields, Jeremy Hellickson and Jeff Niemann
Combined 2012 salary: $18.4 million
Combined 2011 stats: 52-42, 3.25 ERA (288 ER/798 IP), 2.81 K/BB ratio (665 K/237 BB)
Like the Braves, the dynamic here can change if Shields is dealt. However, the right-hander keeps getting more expensive, because of the presence of Matt Moore and because of outside interest due to a lacking free-agent market for starters. Shields bounced back in a big way last season -- going from a 5.18 ERA in '10 to a 2.82 ERA in '11 -- and if he stays, he joins Price and the up-and-coming Hellickson to make the Rays a threat regardless of their payroll and offense. Moore, signed to five-year deal with three additional option years by the Rays on Friday, is on his way, too. Soon, we may have a hard time picking an ace in this staff.
Tigers: Justin Verlander, Doug Fister, Max Scherzer and Rick Porcello
Combined 2012 salary: $28.6 million
Combined 2011 stats: 64-36, 3.49 ERA (327 ER/844 1/3 IP), 3.44 K/BB ratio (674 K/196 BB)
The Tigers have Verlander, the reigning AL Cy Young Award winner and Most Valuable Player, anchoring the rotation. Behind him is Fister, who was one of the best pitchers in all of baseball after coming over from the Mariners, going 8-1 with a 1.79 ERA and only five walks in 70 1/3 innings during the final two months of the regular season. The other two? Full of questions, but plenty of potential. Scherzer notched 15 wins but had a 4.43 ERA -- one year after finishing with a 3.50 ERA -- and the 22-year-old Porcello won 14 games last season but had a 4.75 ERA.
Combined salaries use MLBTradeRumors.com's projected arbitration salaries and estimates $500,000 for players who are not yet arbitration-eligible.