Brewers’ pitching prospect Nathan Kirby has hardly played since being drafted in June of 2015. He had Tommy John surgery on his left throwing elbow in September of ’15 — and then on Tuesday, Brewers’ team doctor William Raasch fixed a nerve issue in the same elbow that will keep Kirby out for another 8-12 weeks. Kirby is 26th on M-L-B Pipeline’s list of Milwaukee’s top prospects. Meanwhile, Brewers’ starter Junior Guerra continues to recover from the strained right calf he suffered while running to first base on Opening Day. Manager Craig Counsell says Guerra completed agility drills Monday — and he’ll have an extended throwing session before Milwaukee hosts Boston tonight (Wednesday).