Peters is developing a slider to use against left-handed hitters, Fabian Ardaya of The Athletic reports.
Though Peters registered a 2.08 ERA against lefties last season, he struck out only 12 of the 92 batters he faced. A more consistent slider could help him generate more swings-and-misses; Peters posted a 28.0 Whiff% on the pitch last season but tossed it only 3.9 percent of the time.