Keller sat between 90-92 mph for much of his spring training outing Wednesday against the Orioles, Alex Stumpf of MLB.com reports.
The decreased velocity is a red flag not only for his potential level of performance but also as a potential indication of injury. However, he completed four innings -- his longest outing of the spring -- and told reporters after the game that he wasn't worried and that his velocity would ramp back up as the intensity of games increased. Though his results were inconsistent, Keller is coming off a breakout season during which he struck out 210 batters across 194.1 innings, and he'll take the mound on Opening Day against the Marlins.