With the signing of Jon Lester, the Cubs' rotation -- which was at least decent in 2014 -- vaults to the top of the heap in the National League Central division, the place where the team will play most of its games in 2015.
The Cubs' rotation now reads, in likely "order," though rotation order is overrated in my view:
One of: Edwin Jackson/Travis Wood/Tsuyoshi Wada/Jacob Turner/Felix Doubront
... with others being in the Iowa rotation to provide backup or injury replacement. The Lester signing takes a lot of pressure off Arrieta, who did a great job as the Cubs' top starter after May 2014. Arrieta now can settle in as a solid No. 2; Hammel is well suited at No. 3, and Hendricks looks like a very good No. 4 guy. Perhaps Jackson will be traded; at this point I'd think Wada has the inside track to the No. 5 spot, but it's very likely going to be an open competition in spring training.
Interestingly, if Wada, Doubront or Turner takes the No. 5 spot, there will be only one 2015 Cubs rotation starter who was in the Opening Day rotation in 2014 -- Hammel. And he left and came back.
Let's take a quick look at the other four N.L. Central rotations as they stand right now.
The Cardinals, by swapping Shelby Miller to the Braves, have put their emphasis on rebuilding their offense rather than concentrating on pitching this winter. Of course, they could always make deals adding to their rotation, but these five are likely to be St. Louis' five starters on Opening Day. It'll likely be Wainwright vs. Lester on Opening Night at Wrigley (though Jake Arrieta has a claim to an Opening Day nod too, after his great 2014).
This is a very solid rotation, though the Cardinals need Garcia and Wacha to return from injuries and for Lackey to forget that he's 36.
I rate the Cubs' rotation as at least the equal to this one and perhaps slightly better.
The Brewers also have Jimmy Nelson, who made 12 starts for them in 2014 and who could beat out Fiers for the No. 5 spot.
This reads like a list of No. 3 and No. 4 starters with only Gallardo being above that level, though Gallardo wouldn't be more than a No. 2 or maybe even No. 3 in the Cubs' rotation at this point. Garza is coming off another injury; he hasn't made more than 30 starts since 2011. The Cubs' rotation is clearly superior.
This is a pretty good rotation, actually. Apart from Cueto -- who has been the subject of trade rumors this winter -- the pitcher who had the best year among those five in 2014 was Simon, who transitioned quite well from the bullpen to the rotation. Whether he can continue that is an open question. Bailey is coming off season-ending forearm surgery and this article from last September suggests he could begin 2015 on the DL. The Reds have Tony Cingrani to take Bailey's place if needed.
The Cubs' rotation also appears better than this one.
The Pirates return their 2014 rotation more-or-less intact with the re-signing of Liriano and Burnett. They have to hope Liriano stays healthy and Burnett, who's returning to a place where he had two fine seasons in 2012 and 2013, doesn't suddenly fade out at age 38. Charlie Morton, who made 26 starts for the Pirates last year, had hip surgery in September and will likely start the year on the disabled list.
Worley was an excellent under-the-radar acquisition by the Bucs last March, showing that injured guys like this can actually pick up their careers where they left off. I would have liked to see the Cubs take a chance on Worley.
The open question for the Pirates is whether their staff will still be as effective without Russell Martin behind the plate. Martin was given a lot of credit for the Pirates' pitching resurgence in 2013 and 2014.
The Cubs' rotation is better than the Pirates', I believe, with the addition of Lester. In summary, it appears the Lester signing has instantly given the Cubs the best rotation in the N.L. Central. Along with a bullpen that got more solid as 2014 went on, the Cubs ought to go into 2015 with one of the best pitching staffs not only in the division, but perhaps in the entire National League.