Doug Davis dropped. Let's be honest, he couldn't do anything.
A brief recap of his season:
A pretty good debut spoiled by some undearned runs followed by excrement. He looked good one other time, June 1 when the Cubs lost a low scoring affair against the Astros (who are terrible hitters). That was his only walk-free performance, and he got 5Ks. Outside of those 2 good starts, his walks were equal to his Ks on the year.
His start vs the yankees will probably be remembered as his best, but 3 walks and 4K? Not dominant by any means. Every once in a while a pitcher gets lucky, and that's what happened that day.
Overall he had a 1-7 record, which is probably about what he deserved. He was a big part of the Cubs fall this season. If the Cubs were 4-5 in those games instead of 1-8, they'd be in better shape.
I think of all the Cubs options, I would roll with Samardzija as the 5th starter until Cashner gets back. He has great K numbers, and starting might help him improve his control.