Jeremy Jeffress is elevating his game to new heights for the Milwaukee Brewers

The Milwaukee Brewers will begin today’s action with the best record in the National League at 35-21. Much of their success to this point can be credited to baseball’s best bullpen, which ranks #1 in the MLB with a cumulative 2.44 ERA after last night’s game. The prosperity of that unit has helped the Cream City Nine thrive in close situations; the team already has four walk-off wins, is 14-5 in one-run games, and is 28-0 in games where they possess a two-run lead at any point in the contest.

Josh Hader has become the face of Milwaukee’s relief corps and a media darling of sorts, and his utter domination of opponents has truly been a sight to see. But Hader isn’t even the hurler in the Brewers’ bullpen who is preventing runs at the highest rate. Right now that title belongs to Jeremy Jeffress, who enters the day with a 0.32 ERA. In 28.0 innings so far this season, the man they call "the starter's closer" because of how often he puts out fires when the initial out-getter runs out of gas, has allowed one singular run all year long in 27 appearances.

Jeffress’ winding career has involved several different stops and more than his fair share of ups-and-downs, but one thing has remained constant - he always thrives while wearing a Brewers’ uniform. Reacquired from Texas at last year’s trade deadline after a disastrous stint in the Lone Star state, Jeffress pitched to a solid 3.65 ERA in 22 appearances down the stretch for Milwaukee. The peripherals didn’t quite match up with the run prevention, though, and once the offseason hit Jeffress was presented with a choice by the front office: sign a non-guaranteed, below-market contract extension with two team options that could buy out the remainder of his arbitration years, or accept a non-tender and become a free agent. Much to the chagrin of the MLBPA, Jeffress and his agent agreed to take Milwaukee’s offer.

Perhaps the peace of mind has helped Jeremy elevate his game to new heights this season. He has allowed only 11 hits this year - including zero home runs - and is holding opponents to a .122 batting average. He’s suppressing hard contact with his 30.3% rate allowed checking in some five percent below the league average, and is keeping the ball on the ground as he usually does with a 57.6% grounder rate. His 2.57 BB/9 rate would represent a new career-best total, and he’s missing bats like never before - his 24.5% strikeout rate would also be a career-high, and he’s bested his current 10.9% swinging strike rate in only one other season.

The Jeremy Jeffress that we are seeing dominate opponents right now is a different one than the fella that we watched save 27 games in 2016 before that ill-fated (for Jeffress at least) midseason trade to the Rangers. He’s not throwing quite as hard these days as he once did, but his heater is still no joke and crosses the plate at an average velocity of 95.6 MPH. For most of his career Jeffress has overwhelmingly relied on his sinker as his primary offering, but that is no longer the case. Jeremy has reduced his sinker usage from as high as 70% in 2014 all the way down to 31.6% this season, and while it’s still technically his “primary” pitch in terms of usage rate, he mixes his pitches at pretty close percentages overall.

At the expense of his sinker, Jeffress has increased the usage of his four-seamer this season. He’s throwing the pitch 26.8% of the time, which would be his highest four-seam usage rate since his truncated 2012 campaign with Kansas City, before he even added a sinker to his arsenal. Jeffress has mostly avoided the four-seamer through his career, and with good reason - through the end of 2017, batters had hit .306 against the pitch in his career. This season, however, opponents are batting just .100 against the offering, and Jeffress has racked up six punchouts on his fastball.

The newfound success has no doubt been due to a change in the way Jeffress is utilizing the pitch. Similar to the adjustments made by Junior Guerra that we’ve explored previously, Jeremy has begun to elevate his fastball with much more frequency this season. Also like Guerra, Jeffress is one of baseball’s major spin-rate gainers - he’s imparting an average of 2245 RPM of spin rate on his four-seam fastball, an increase of 114 revolutions per minute over last season. That’s helped him generate a two percent increase in whiffs on the pitch and has made for a much more effective offering in the eyes of Pitch Info’s linear weights; Jeffress’ wFA (weighted fastball runs above average) so far this season is +3.0 runs, while his career wFA was entering 2018 was -9.5 runs.

Also integral to Jeffress’ success has been the introduction and development of a split-finger fastball to his cache of pitches. Jeffress first learned the pitch in 2016 when he asked Junior Guerra to show him his split-finger grip, but he didn’t really start to work it into a regular part of his arsenal until his return to Milwaukee last summer. Jeffress had leaned on his outstanding curveball as his primary offspeed pitch throughout his career, but now this season he’s throwing his splitter (18.3%) nearly as often as his Uncle Charlie (22.6%). It’s hard to argue with the strategy, as batters are hitting only .179 against the splitter and it’s generating the highest whiff rate of any of his pitches. It’s also given him a reliable weapon to use against left-handed hitters, erasing what had previously been more than 100 points of OPS difference in terms of platoon splits during his career. This year, lefties are actually hitting worse against Jeffress (.315 OPS) than right-handers (.382 OPS).

No, Jeremy Jeffress isn’t likely to finish the season with an ERA+ of 1278. There will undoubtedly be some regression to his .167 BABIP and 95% strand rate, but even in the eyes of FIP- (54) and DRA- (67), he’s been an indisputably elite relief pitcher this season when stripping away all other factors. The narrative about Jeffress’ career has long been that there’s something he likes in the water in Milwaukee - he owns a 2.25 ERA in 207 appearances with the franchise that made his the #16 overall pick way back in 2006, and a 4.76 ERA in 91 appearances during the other three stops he’s made as a big leaguer. But more than just that, Jeremy Jeffress has evolved into a more complete pitcher now at age 30, boasting a four-pitch arsenal and the ability to retire batters on both sides of the plate. we could very well see history with his next appearance, too - if Jeffress can put up a scoreless outing whenever he takes the mound, it would be his 24th consecutive scoreless appearance, which would set a new franchise record for the Milwaukee Brewers.

Statistics courtesy of Fangraphs, Baseball Prospectus, Brooks Baseball, and Baseball Savant