Bailey Falter's improved fastball, breakout season seem to be a Pirates fluke

When Bailey Falter took a no-hit bid into the seventh inning last Wednesday, he seemed miles away from the pitcher with a 0-7 record that the Pirates picked up from the Phillies at last year’s trade deadline. Falter has become a reliable member of Pittsburgh’s rotation largely on the strength of one pitch: his four-seam fastball. His success this year, though, seems too good to be true.

As of September 16, Falter’s four-seam fastball is worth 6.5 runs above average. That’s the fifth-most valuable fastball among lefties with at least 120 innings pitched this season. Last season, his fastball resulted in a -0.5 run value. This reversal of fortune seems to explain Falter’s rise from DFA candidate to rotation mainstay, but signs seem to point to a regression in 2025.

Bailey Falter’s fastball has been the key to his success in 2024, but his exemplary results may be due to luck.

Falter, a lefty, tends to throw his fastball across his body so that it works up-and-in to right-handed batters. This allows his slider to play down-and-in from a right-handed perspective and his sinker to cover the outside bottom corner. Fortunately for Falter, batters in 2024 have the worst stats against fastballs in that zone compared to any other season in the past decade. In other words, Falter’s fastball isn’t necessarily good; the batters he’s facing are particularly bad.

Falter’s success also seems to be the result of luck. His expected statistics all rank in the bottom 10% of the league, and the difference between his wOBA and xwOBA on his four-seamer is .015. More pronounced is the difference between his expected and actual stats on his sinker. Despite getting hit hard nearly 60 percent of the time and having an expected slugging of .640, Falter’s sinker has a plus-2 run value per Statcast.

These numbers are untenable. Bailey Falter is who we thought he was. In some ways, he’s worse. His walk rate and hard-hit rate are both at a career high. As such, the Pirates’ current path forward seems clear. Use Falter’s streak of good luck for as long as it holds out. Allow him to carry the load in the rotation in an injury-plagued year. But don’t weep when the next round of Pirates rookies rise to take his place.