Glasnow debuted a slider as part of his arsenal in his relief appearance Friday against the Cardinals after experimenting with the pitch in flat-ground sessions earlier in the week, Bill Brink of the Pittsburgh Post-Gazette reports.
During his three shutout innings Friday, Glasnow broke in the slider for six of the 33 pitches, including his final throw of the night that struck Kolten Wong out swinging. The new pitch was instrumental in Glasnow delivering his best showing of the season, as he allowed only three of the 12 batters he faced to reach base while finishing with four strikeouts. Since Glasnow hasn't had the opportunity to get a good feel for his curveball while working out of the bullpen this season, it appears the slider could become his new go-to breaking ball, which would likely aid his chances of finding success against opposite-handed hitters like Wong. Lefties have posted a .913 OPS against Glasnow this season, a 456-point increase from the mark he has allowed versus right-handed hitters.