The left-handed pitcher should be returning from a broken right arm within the next two weeks. Current speculation is that he'll come back for a start against the New York Mets on May 10, but we'll see what the Pirates do if Jeff Locke adds to his current streak of 13 scoreless innings this weekend against the Washington Nationals.
If Locke does well, the Pirates shouldn't be in any rush to bring up Liriano. The Nationals did something similar with Chien-Ming Wang last season, keeping him on a rehab assignment in the minors for perhaps a few weeks longer than necessary because of how well his replacement (Ross Detwiler) had been doing. Wang only made four starts before being re-replaced by Detwiler.
It should be noted that there's an atypical clause in Liriano's contract—which should be in the contract of anyone with an injury history, in my opinion—that bases pay incentives on the amount of time spent on the disabled list. The sooner they bring Liriano up, the more they owe him this season. So, if there's any doubt over whether he's at full strength, the Pirates will have every incentive to let him continue stretching out in the minors.
Also, it wouldn't be proper analysis of Francisco Liriano if we didn't mention how horrendously inconsistent he can be. Here are his stats from four consecutive starts early in the 2011 season:
April 27 vs. Tampa Bay: 3.0 IP, 6 H, 7 ER, 4 BB, 4 K
May 3 at Chicago: 9.0 IP, 0 H, 0 ER, 6 BB, 2 K
May 10 vs. Detroit: 3.0 IP, 3 H, 4 ER, 3 BB, 1 K
May 17 at Seattle: 7.0 IP, 3 H, 1 ER, 1 BB, 9 K
Liriano has had an ERA over 5.00 in three of the last four seasons and an xFIP greater than 4.00 in four of the last five. Yet, he could strike out 15 guys or throw a no-hitter at any given time. He may be back soon, but who knows what Pittsburgh will be getting.