#3 Spencer Arrighetti
The fact that Spencer Arrighetti didn't debut last year was somewhat surprising. At times he looked unhittable in the minor leagues.
A bad April and a bad September slightly inflated his season numbers (4.40 ERA and 1.25 WHIP), but from May-August, his five-pitch arsenal looked every bit the part of a big league starter.
The Astros finished last year with a totally depleted pitching staff. If they decide to spend their money on contract extensions rather than free agent acquisitions, they could rely on internal pitching depth to address their void. His stuff pure isn't Hunter Brown level, but it's better than J.P. France.
He can be a middle of the rotation piece for a big league club. If Houston bets on one arm inside their system to be a key cog of next year's team, its Arrighetti.