As of Saturday March 21, it looks like the rotation will consist of the following.
RHP – Scott Feldman
RHP – Collin McHugh
LHP – Brett Oberholtzer
While the Astros don’t have a Clayton Kershaw or Madison Bumgarner type of ace, Keuchel and McHugh made a huge leap in 2014. The ace of the Astros is Dallas Keuchel, because he was a great breakout player in 2014. He is the ace based on his numbers from last year.
At his best, Scott Feldman is an average but dependable pitcher based on his resume. He will end up with a mid three ERA with an even 11-11 won-loss record. Nothing exciting, just will get the job done most of the time.
Collin McHugh may still be unproven, but should be the pitching staff’s leader in strikeouts. He has pitched well so far this spring.
Brett Oberholtzer has the potential to be an above average starting pitcher, he just needs to learn how to be more efficient with his pitches to pitch deeper into games.
Asher Wojciechowski has out-pitched the competition so far in the spring, only giving up one run in 12 innings. He is a strike thrower. Dan Straily offers the veteran experience for the rotation, and Mark Appel’s time is coming, but not opening day.
I would give the starting rotation a B –