Hu was optioned to Triple-A Durham on Wednesday.
While Hu is nearing his big league debut, he didn't have a realistic chance of breaking camp on the 25-man roster. He famously features a palmball, and used his funky pitch mix to post a 2.59 ERA, 1.15 WHIP and 107:36 K:BB in 142.2 innings at Double-A last season. Hu projects as a No. 4 or No. 5 starter in the big leagues.