Breakout Breakdown: Jeremy Jeffress

An extraordinarily deep and effective bullpen was a key part of the Brewers’ run to the NLCS and coming within a win of going to the World Series. While they got just 20.1 innings from their starting pitchers in their series against the Dodgers, Josh Hader and Corey Knebel each tossed at least seven innings apiece, allowing a combined one run between them.

Jeremy Jeffress was as much a part of that vaunted bullpen throughout the regular season, but he faltered in both the NLCS and the NLDS against the Rockies. Despite collecting 11 strikeouts in eight postseason innings, Jeffress allowed six runs on 16 hits (including two home runs) and four walks.

The low point for Jeffress may have been in Game 2 of the NLCS, when he allowed Justin Turner’s two-run homer that put the Dodgers ahead for good and enabled them to head to Los Angeles with a 1-1 split. After the game, Jeffress called the homer “lucky,” and then on the following day, he tweeted that he meant that the hits he allowed prior to Turner’s shot were lucky. As Jeffress’ postseason .410 batting average allowed was 132 points higher than his xBA (per Baseball Savant), there may have been something to his explanation for his woes.

Regardless of what we can or can’t make of Jeffress’ eight postseason innings, there is no denying that he had a spectacular breakout season in 2018, most of which preceded his 31st birthday. Despite getting just 15 saves, Jeffress ranked seventh among relievers in Roto value, according to ESPN’s Player Rater. Racking up eight wins helped his cause, but Jeffress was an across-the-board contributor with a 1.29 ERA, 0.99 WHIP and 89 strikeouts across a career-high 76.2 innings.

In each of his previous four seasons (2014 was his first year with at least 30 innings), Jeffress had never compiled a strikeout rate as high as 24 percent, but in 2018, his rate soared to 29.8 percent. As one would expect, he also posted a career-high swinging strike rate. Jeffress’ 13.5 percent mark was more than two percentage points better than his previous best for a full season (11.4 percent in 2015).

He was better at getting whiffs on both his four-seam fastball and sinker, but it was a change in his pitch mix that was critical to his strikeout surge. Jeffress cut his sinker usage from 47.5 percent in 2017 to 28.2 percent, so he became far less reliant on his worst pitch for swings-and-misses. Many of those sinkers were replaced with curveballs, as he upped his usage rate from 18.9 to 30.8 percent. Not only was Jeffress using his curveball more liberally, but he was getting more movement and spin on it as well. That likely enabled him to increase his swinging strike rate on the pitch from 15.2 percent last season to 18.5 percent this year.

The potential danger is swapping out sinkers for curveballs is that the latter pitch has been inferior for inducing grounders. That trend continued this season, as Jeffress’ sinker ground ball rate was 60.3 percent, while his rate on curveballs was a more modest 46.5 percent. Yet he allowed just a single home run on a curveball throughout the regular season. (However, Yasiel Puig’s homer in Game 7 of the NLCS was off a Jeffress curveball.)

Even if we want to assume that Jeffress will continue to avoid homers on his curveball next season, can we also assume that the pitch will be as effective for getting whiffs? The surge in Jeffress’ curveball swinging strike rate did not materialize until the beginning of June. At that point, Jeffress started to locate his curveball towards the center of the lower edge of the strike zone, as opposed to down and away against righties (and down and in versus lefties).

Jeffress was able to maintain the shift in location throughout the remainder of the season, and the graph below shows, he was able to get more swings on his curveball through the final four months of the regular season as well as the postseason. If we were inclined to be optimistic, we could note that Jeffress has been consistent over the better of the last five months in getting batters to swing after his curveball and not do much with it. If we are to be skeptical, we would emphasize that Jeffress’ improvement as a strikeout pitcher has not even lasted a full season. While he had a 33.0 percent strikeout rate from June 1 forward, his rate was a mere 23.8 percent before that.

Buying into Jeffress’ strikeout rate can boost our confidence in him going into 2019, but we still can’t be too certain about how well he will fare in the other categories. Even though Jeffress led the Brewers in saves in the second half, that was partially because he was afforded more opportunities due to the struggles of Knebel. We can’t assume that Knebel won’t be better next year or won’t get more consistent save opportunities.

Jeffress’ minuscule ERA was shrunk by a 92.9 percent strand rate that was probably too good to be true. Also, in allowing only 16 hits on the 36 line drives batted off him, Jeffress likely got some additional ERA and WHIP help. If he had allowed hits on line drives in play at the average rate for the majors, he would have given up eight additional base hits. That alone would have raised his WHIP by 11 points.

In short, the odds of Jeffress being a top-10 fantasy reliever in 2019 are small, unless he somehow manages to be the Brewers’ primary closer for the vast majority of the season. If he is in a committee and gets between 10 and 15 saves, Jeffress will still need to come close to this season’s win total and ERA and WHIP to be a top reliever again, and that seems unlikely. He may be able to approach this year’s strikeout total, but even that is too much of a gamble to assume, given the relatively short duration of his recent strikeout surge.

In the recent 2 Early Mocks, Jeffress achieved a 229.9 ADP, just a few spots below Zach Britton and Arodys Vizcaino and a dozen spots ahead of Archie Bradley. That looks just about right. There are plenty of relievers with better save potential and similar (or better) strikeout upside whom you can pursue in the middle rounds.