Who to bring up to take a start?

The Giants were already forced to bring up somebody to take Jerome Williams turn next Tuesday but apparently Schmidt's arm hasn't rebounded as fast as expected and now there is talk about pushing his start Sunday to Monday to give him more rest (ironic since they skipped Williams turn in the rotation, after he pitched so well in his first game and thus screwing up his rhythm, so that Schmidt could pitch on his normal day). So who to bring up to take his start on Sunday?

Right now the two main candidates are Brad Hennessey and Matt Cain - Jesse Foppert would have been in the mix if he wasn't walking so many batters. Misch has done well also but Cain has a 1.75 ERA in 4 games, 25.2 IP with only 10 hits but 11 walks and 29 strikeouts while Hennessey has a 2.45 ERA in 4 games, 25.2 IP with 19 hits and 9 walks and 21 strikeouts, whereas Misch has a 3.05 ERA in 4 games, 20.2 IP with 20 hits and 6 walks and 13 strikeouts. Foppert, FYI, has a 3.46 ERA in 3 games, 13.o IP with 12 hits and 10 walks (!) and 13 strikeouts. Those are all good ERAs in any setting but they are especially good for pitchers in the offense-happy PCL.

Hennessey would seem to be the front-runner on a number of fronts. First, he has had major league experience already and so there would be less of an adjustment and less of a surprise for him. Second, bringing up Cain would start his clock ticking on callups. Third, perhaps most important of all, he is probably the best trading chip of the pitchers that the Giants has not made untouchable (I assume Cain, Foppert, Aardsma, and Valdez are untouchable) though perhaps Misch is pretty close right now and this would be a good way to showcase him.

I normally would not advocate trading him because he seems to be a pretty good prospect with less question marks than, say, Boof Bonser, but the Giants are loaded with strong pitching prospects and so he and Misch (who is Lowry-like, only better thus far) are probably the ones most valuable that they have on the block.

I've also wondered if since Misch has outperformed Lowry at equivalent levels, the Giants might package Lowry in a trade once Misch is ready to come up or perhaps once Cain is ready to move up to the MLB. Perhaps Detroit would be willing to take Lowry for Urbina mid-season if they were interested in Jerome Williams previously.