Jenifer Langosch tweets that Ross Ohlendorf has said it will likely be another month before he can join the rotation. Also, Neal Huntington said on his show yesterday that Ohlendorf would definitely make some rehab starts before rejoining the club. May 15-June 1 would seem to be the target at this point.
Even though Brian Burres had a great start yesterday for Indianapolis, I think Brad Lincoln is the obvious candidate to spend most of the time the rotation because Burres is not currently on the 40-man roster. Karstens is better suited to the long relief role, and the Pirates can send Dan McCutchen down and bring Lincoln up and have the staff set up in a way that would seem to work best without having to designate another player for assignment.