Breakout Breakdown: Walker Buehler

In a postseason where David Price, Clayton Kershaw and Luis Severino have hit some snags, it’s hard not to be impressed by the recent showings of Walker Buehler. In his first-ever postseason appearance against the Braves on Oct. 7, the 24-year-old rebounded from a five-run second inning to toss three perfect frames.

On Monday night, Buehler was outdueled by Jhoulys Chacin, but he cruised through his first five innings, allowing a run on two hits with eight strikeouts. While the Brewers padded their lead in the sixth and seventh innings, the two-run homer by Orlando Arcia that doubled their advantage to 4-0 had a hit probability of just 22 percent, according to Baseball Savant.

Aside from the time he missed in June and July with a rib cage microfracture — and a disastrous one-inning appearance he made in between two DL stints for the injury — Buehler was a remarkably steady producer in his rookie season. Only five of his 23 starts culminated in a game score under 45, and his ERA never rose as high as 4.00. He finished 8-5 with a 2.62 ERA, 0.96 WHIP and 151 strikeouts over 137.1 innings.

To compare Buehler’s numbers before and after his rib injury, it appears as if he glided through the entire season, with a slight uptick over the latter half of the season. In both portions of his season, Buehler posted an ERA in the 2.00s and a WHIP below 1.00, though the 2.7-percentage point increase in strikeout rate he enjoyed over his final 14 regular season starts was offset by by an increase in walk rate and a downturn in ground ball rate.

A more granular breakdown tells a different story. If Buehler’s 2018 season was a breakout, then his performance over the final month of the season was a breakout within a breakout. Over his last six starts, he posted a 1.62 ERA and 0.77 WHIP with a 30.6 percent strikeout rate. Some of the improvement in ERA and WHIP can be traced to a .186 BABIP, and while that is not sustainable, Buehler was able to prevent hits by inducing soft contact at a 30.7 percent rate. (The major league average for soft contact rate in September/October was 18.0 percent.) Only two other pitchers — Jacob deGrom and Chris Sale — had at least one month this season in which they threw at least 30 innings and compiled a soft contact rate above 30 percent.

Through the end of August, Buehler was able to record a healthy 26.9 percent strikeout rate in spite of a swinging strike rate of just 9.6 percent, as he pounded the strike zone (48.0 percent Zone%) and got called strikes at an above-average rate (18.9 percent). From September on, he did not need to freeze batters in order to strike out more than three out of every 10 batters, as 87 (or 14.9 percent) of his 585 pitches resulted in swings-and-misses.

Coinciding with his dramatic increase in swinging strike rate, Buehler started to generate more movement on his four-seam fastball. As the graph below depicts, that trend has continued through his two postseason starts to date. Over his eight starts since the beginning of September (including postseason), Buehler has a 16.2 percent swinging strike rate on his four-seamer, as compared to the 13.9 percent rate he established prior to that this season (per Brooks Baseball).

The ability to avoid contact and induce soft contact at elite rates, even over a month’s time, is rare, but what if Buehler’s late-season performance is less of a breakout and more of a small sample artifact? Because his best years are presumably ahead of him, we should figure his skill set should improve from what he showed through his first four-and-a-half months of 2018. That improvement won’t necessarily come in 2019, and if it doesn’t, Buehler may be the harder-throwing clone of Jake Arrieta, circa 2017 — a good-but-not-great strikeout pitcher who relies on freezing batters and soft contact to maintain an ERA and WHIP well below the major league average.

This is not meant as a put-down. Last year, Arrieta ranked 25th among starting pitchers in Roto value, according to ESPN’s Player Rater, and that position probably comes closer to Buehler’s floor than his ceiling going into 2019. In the recent 2 Early Mocks, Buehler’s ADP (63.8) ranked 19th among starting pitchers. If that draft position were to hold until next March, Buehler would still be coming at a reasonable cost, even if he barely wound up squeaking into the top 25 at the season’s end.