Owens had a rough spring training, but he did manage a 2.40 ERA, 1.10 WHIP, 10.1 K/9 in AA last year at age 21.
In comparison, Weiland had a 4.42 ERA at AA at age 24.
Doubront had a 3.35 ERA, 1.41 WHIP, 8.2 K/9 in AA at age 22.
Bowden had a 4.28 ERA, 1.43 WHIP, 7.6 k/9 in AA at age 20.
Owens is the only guy who has been a no-hitter threat every minor league start. It will take him time, but he'll get here.