2012 was a watershed season of bad for the Cubs.
The combined WAR (wins over replacement value) for all pitchers who started in 2012 was a 1.7.
Two starters are returning, Garza (1.0 WAR) and Samardzija (1.6 WAR).
Lost are Dempster's 3.3 WAR and Maholm's 1.4 WAR, which shows how bad the bullpen was when the total team pitching WAR was a negative 0.1.
The collective bullpen was a negative 1.8. If AAA talent is 0.0 WAR, the bullpen would have rated almost two levels below that talent tier (AA-A).
So the question remains, if the rotation is the key to 2013 pitching, have the off-season acquisitions been better than what has been lost or traded away?
Can Baker replace Dempster's 3.3 WAR? He did not pitch in 2012, so from that standpoint one would say no. In 2011, with the Twins, Baker had a 4.2 WAR with a pre-Tommy John surgery mechanics. He may not be back to open the season. So if you expect some quality with Baker starts, a 2.1 WAR projection will not reach replacement level for Dempster.
Can Feldman replace Maholm's 1.4 WAR? He made 21 starts for Texas in 2012, but also got demoted to 8 games of bullpen duty. Feldman's 2012 WAR was 0.0, or mere AAA level. So Feldman does not project to reach replacement level for Maholm.
Can Villanueva replace Volstad's horrible negative 1.9 WAR? Yes, Villanueva made 16 starts in his 38 games played, and had an overall 1.2 WAR.
So the off-season acquisitions to replace Dempster, Maholm and Volstad have a combined 2012 WAR of 1.2 (or 3.3 if you expect a healthy return of Baker.) The Cubs need to replace 2.8 in combined Dempster, Maholm and Volstad WAR to just keep the status quo in the pitching staff.
So the Cubs would have been paddling against the tide until they signed Edwin Jackson to a four year deal. A deal so long, that Edwin may be actually a Cub when the team is expected to be competitive in 2016.
Jackson had a 1.6 WAR with the Nationals last season. The scoop is that he is a rollercoaster type pitcher: he will have a brilliant outing, followed by a dud, following by an average outing. However, the signing of Jackson to replace Feldman would give the 2013 rotation a 2.8 WAR + which would be on par for potential improvement.
However, Hoyer apparently told Feldman that he would be a starter with the Cubs. How promises may come back to bite. Take Villanueva out of the rotation, it may help the bullpen, but the new rotation replacement WAR goes down. It is 1.6 to 3.7, so the success of the new rotation could go either way depending on how well Baker pitches coming off major surgery.
