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Jack Flaherty is the MLB playoffs’ hottest pitcher

Minuscule 0.91 ERA since the All-Star break

St Louis Cardinals v Arizona Diamondbacks Photo by Norm Hall/Getty Images

The St. Louis Cardinals were floundering at the All-Star break, and so was 23-year-old pitcher Jack Flaherty, in his second season. But Flaherty turned in one of the best second-half runs in baseball history, fueling the Cardinals’ ascension to the top of the NL Central and the first postseason for St. Louis in four years.

A loss in the first game after the All-Star break dropped the Cardinals below .500, at 44-45. Only five teams had a worse record in the National League at the time, but thanks to a lackluster division they were only three games out of a playoff spot. Their quest for the postseason was in reach, but they needed a boost from Flaherty, whose 4.64 ERA ranked 62nd among 78 qualified pitchers.

Look what happened next

  • He allowed just 11 total runs in his final 15 starts, posting a microscopic 0.91 ERA, the third-best post-break ERA in MLB history.
  • He pitched in 100 different innings after the All-Star break, 91 of which were scoreless.
  • In nine of his final 15 starts Flaherty did not permit a run. The only other pitchers to do that over the entire season were Hyun-jin Ryu with 10 starts and Zack Greinke with nine. Flaherty did that all after the All-Star break.

So, how’d he do it?

Flaherty doesn’t possess a blazing fastball, though at 93.9 mph he’s in the upper third in velocity. His slider is his wipeout offering, a pitch he threw 27.5 percent of the time yet accounted for 39.4 percent of his strikeouts. After the All-Star break the pitch was even more devastating, with opposing batters hitting just .099 against it with 48 strikeouts and only one extra-base hit.

He struck out double digits in four starts after the break, and whiffed nine in three more outings. Flaherty allowed zero or one run in 13 of his final 16 starts, pitching like the ace St. Louis was counting on.

“It’s unlike anything I’ve ever seen. This is his first full season where he was expected to go out and do great things,” Cardinals veteran pitcher Adam Wainwright told the St. Louis Dispatch. “He brought it home. Second half of the season ... that was incredible. Every single start was zero, zero, zero, zero.”

The Cardinals were 47-27 since the All-Star break, including 10-5 in Flaherty’s starts, to win their first division title since 2015.

St. Louis lore

An historically great pitching run by a Cardinals starter means we’re legally obligated to bring up the fact that Bob Gibson posted a minuscule 1.12 ERA for an entire season in 1968, and did so in an absurd 304⅔ innings. That was famously the Year of the Pitcher, a season with offenses so barren that MLB lowered the mound the very next year to tip the scales back toward hitters.

This season was the Year of the Home Run, an environment antithetical to the one in which Gibson thrived over five decades ago. It also illuminates just how impressive Flaherty has been during his stretch run. Still, it’s fun to compare, so here is Gibson’s best 15-start stretch in 1968 — from May 17 to July 30 — compared to Flaherty’s post All-Star break excellence in 2019.

A pair of great Cardinals pitching stretches

Gibson 1968 12-3 133⅔ 11 11 3 23 107 0.74 0.733 .162/.208/.205
Flaherty 2019 7-2 99⅓ 11 10 5 23 124 0.91 0.715 .142/.208/.217

The general rule is if you’re a Cardinals pitcher whose mound work evokes Bob Gibson, you’re on the right track.

Avoiding the long ball

Home runs were inescapable this season, with records galore set across the league. Flaherty fell victim 20 times to the home run ball in 18 starts before the break, which helped fuel that 4.64 ERA.

But since the break the right-hander has been remarkably stingy, allowing only five home runs in 15 starts. Three of those shots were solos, and he allowed seven runs via the home run in his second-half surge (amazingly, Flaherty gave up only four other runs during that stretch).