The 26-year-old Black has thus far spent his entire professional career with the Giants, who selected him in the seventh round of the 2011 amateur draft. Black ascended to the Double-A level last year and, thanks to an outrageous walk rate (9.19 per nine innings), recorded a 4.88 ERA across 31 1/3 frames. At the same time, he did strike out 15.22 batters per nine, and Black posted both sky-high strikeout rates and better walk rates from 2014-15.
Gardeck, like Black, entered the pros as a Giants draft pick, going in the 16th round in 2012. He missed all of 2016 on account of Tommy John surgery, but the now-26-year-old produced the previous season at the High-A level, where he logged a 3.54 ERA, 10.84 K/9 and 2.5 BB/9 in 86 1/3 innings.