Keller made his Grapefruit League debut Sunday, throwing two scoreless innings against Boston. He allowed two hits and no walks while striking out three batters, Lance Lysowski of DK Pittsburgh Sports reports.
"There was nothing to be disappointed about today," manager Clint Hurdle said. "Efficient, crisp, downhill angle to the fastball with firm velocity." The righty now features an improving changeup to go along with his fastball and curveball. "It's huge," Keller said. "Having that third pitch to keep in the back of hitter's minds is huge. It's been a big progression for me, and it's coming along nicely." Keller will start the 2018 campaign with Double-A Altoona, and while he's got an outside shot of making his major-league debut in September, the Pirates typically promote their prospects more slowly than do other organizations.