They added Travis Wood, Ian Stewart and Anthony Rizzo to the fold via trade, signed free agents Paul Maholm and David DeJesus, claimed Luis Valbuena off waivers and replaced manager Mike Quade with current skipper Dale Sveum.
They flipped Maholm and Ryan Dempster at the trade deadline, and the team finished 61-101 one year after finishing 71-91.
This winter, Epstein and Hoyer have become more aggressive in overhauling the Cubs, and their emphasis has been run prevention.
The Cubs have since re-signed reliever Shawn Camp (one-year, $1.35 million), signed Japanese reliever Kyuji Fujikawa (two-years, $9.5 million), and starters Scott Baker (one-year, $5.5 million), Scott Feldman (one-year, $6 million), Carlos Villanueva (two-years, $10 million) and now Jackson.
Baker, Feldman, Villanueva and Jackson join a rotation that also includes incumbents Matt Garza, Jeff Samardzija and Travis Wood—giving them seven starters for five spots. However, with Baker still rehabbing from Tommy John surgery, such depth shouldn't be a problem initially.
Feldman, Villanueva and Wood all have experience out of the bullpen. Thus, when Baker is ready, the Cubs will have plenty of flexibility at their disposal.
Baker, Garza and Feldman can all become free agents after the season, so the Cubs can deal them at the deadline for prospects, as they did with Dempster and Maholm last season.
I grouped the Cubs' current starters together over at FanGraphs today. I was surprised at how similar Samardzija, Garza, Baker and Jackson have been over the last three seasons when measured by their Expected Fielding Independent Pitching (xFIP), which is an advanced metric scaled to ERA based on a pitcher's strikeout, walk and home run ratios:
Samardzija: 3.71 xFIP
Garza: 3.72 xFIP
Baker: 3.74 xFIP
Jackson: 3.74 xFIP
Not much difference there. Samardzija converted to starting last season, so he has only one year of rotation experience under his belt. Garza missed the second half of last season with an injury and Baker missed part of 2011 and all of 2012 due to injuries. Jackson has been the most valuable of the four because of his durability.
The Cubs should improve upon the National League's third worst rotation ERA from last season with the additions that they've made this winter.
In addition, Nate Schierholtz— the only significant position player that the team has added this winter—should improve the club's defense in right field next season. The Cubs' defense finished in the middle of the pack in 2012 by converting nearly 71 percent of balls in play into outs.
Alas, they also finished third worst in runs scored in the NL last season. Even with expected improvements from young sluggers like shortstop Starlin Castro and first baseman Anthony Rizzo, it's hard to imagine Chicago improving enough offensively to compete with the Reds and Cardinals just yet.
But even with contention unlikely, Epstein and Hoyer are smart in using their large market resources to strengthen the team through improved pitching and defense. The new Collective Bargaining Agreement (CBA) severely limits their ability to spend on amateur talent in the draft and on the international market, so they might as well use their resources to acquire big league talent that they can later flip for prospects.
Of course, the Nationals, A's and Orioles didn't look good enough to contend on paper prior to 2012, and all three squads shocked most pundits by making the postseason. With the advent of the second wild card, perhaps the Cubs could sneak into the playoffs next year.
If they do contend in 2013, it will likely be due to the improvements that Epstein and Hoyer have made to the pitching staff this winter—particularly the starting rotation.