The Return of Francisco Liriano

Francisco Liriano is back. After a month-long banishment to the bullpen, Liriano has returned to the rotation looking like a completely different pitcher. In his six starts prior to his demotion, Liriano was broken. The lefty allowed 37 hits in just 26.2 innings, and racked up a 9.45 ERA. While his stint in the bullpen only lasted five outings, it seemed to be exactly what he needed. Since rejoining the Minnesota Twins’ rotation, Liriano has allowed just 16 hits in 30.1 innings, and has posted a 2.67 ERA. Even though there are some reasons to doubt Liriano’s recent performance, there are also some signs that his success could be due to an altered approach.

There’s good reason to be skeptical about Liriano’s turnaround. He’s only made five starts since he returned from the bullpen, and those starts haven’t been against strong offensive opponents. Over that period, he’s only faced one team — the Milwaukee Brewers — with an above-average wRC+. While Liriano gave up 3 runs over 6 innings in that start, he actually carried a no-hitter into the sixth inning. But after walking two batters to open the sixth, Ryan Braun hit a three-run homer. That was the only hit Liriano allowed in six innings. It might be easy to look at Liriano’s performance and write it off as a hot streak, but that’s not necessarily the case.

As the season has progressed, Liriano has been throwing fewer four-seam fastballs.

Liriano’s numbers in April cover his first four starts, when he was terrible. May is a bit of a mixed bag, as Liriano made two starts, was sent to the bullpen and then returned to the rotation for one start. And the June section covers Liriano’s last four starts.

Liriano had been gradually throwing more sinkers and sliders as the season progressed, and it’s come at the expense of his four-seam fastball in June. After relying heavily on the four-seamer through the first two months of the year, the pitch has accounted for just 16% of his repertoire this month.

It seems to be paying off. Liriano’s fastball has never been a great pitch. Since 2008, the pitch carries a -34.8 pitch value according to the PITCHf/x data. Liriano’s sinker hasn’t fared much better, with a -9.7 pitch value since 2009 — but it’s still been more effective than his four-seamer. Since Liriano can’t completely scrap his fastball, he’s at least limiting the damage done against him by throwing the sinker more often.

The reliance on the slider has really been the key for Liriano. While it’s worrisome that Liriano is throwing it 37% of the time in June, it’s also easily his best pitch. Throughout his entire career the slider has always received a positive pitch type value. This season is no different, as Liriano’s slider currently has a 3.1 pitch value.

Throwing his best pitch more often is obviously going to help, but Liriano has also been getting better results with his slider as the season has moved forward.

In each month, Liriano has managed to induce more swings and misses with the slider. Getting batters to swing and miss 27.21% of the time is incredibly impressive. His four-seamer — for example — has only induced a whiff 3.45% of the time this month. Liriano has also been able to get more ground balls with his slider. That’s a recipe for success.

In the past, Liriano has struggled when the Twins have asked him to alter his repertoire. But with the trade deadline looming, and Liriano slated to be a free-agent, the Twins are done tinkering. While Liriano’s approach is risky — considering the frequency at which he throws his slider — it’s been the driving force behind his success his entire career. It’s also been the biggest factor behind his most recent resurgence.

*The stats used in the charts were taken from BrooksBaseball.net.