Lieber the key in trading Marquis

Looking at Saturday's box scores from the Cubs split squad games, I noticed something very interesting that Jon Lieber threw four shutout innings against the D-Backs. I know it wasn't the full Arizona lineup that Lieber was facing but seeing that performance is starting to make me think that Lieber is gaining control on the fifth spot in the rotation. Jason Marquis has made it clear that he wants out and his second-half performances the last 2 years have shown he can't be trusted after July 1. Now all the Cubs need is a No. 3 starter and possibly a center-fielder since Pie and Fuld aren't exactly ripping the cover off the ball right now. Only 3 more weeks till the regular season begins and still too many questions.