For half of the 2018 MLB regular season, Junior Guerra was the ace of the NL Central champion Milwaukee Brewers. Left off the Opening Day roster after a promising spring, Guerra was nonetheless called upon to make his first big league start of the year on April 11th. He delivered 5.1 innings of one-run ball at Busch Stadium against the St. Louis Cardinals, out-dueling Adam Wainwright as the Brewers won the game by a score of 3-2.
On July 8th, Guerra completed his 17th start of the season, six innings of one-run pitching in a 10-3 defeat of the Braves. His season line sat at a 2.79 ERA across 93.2 innings. Then, in his final outing before the All-Star break, disaster struck. Guerra coughed up nine hits and six runs across in four innings against the Pittsburgh Pirates, and the next day, he was placed on the disabled list with one of the most alarming ‘minor’ injuries in baseball - forearm soreness. He did return to the mound 10 days later, but it didn’t take long for it to become clear that Guerra’s effectiveness had diminished. The splitter-specialist couldn’t locate that pitch where he wanted it and too often was working behind batters. Over his final eight starts after returning from the DL, he ralphed up a 6.99 ERA in 37.1 innings. Gio Gonzalez, acquired in advance of the August 31st deadline, took over Junior’s rotation spot down the stretch in September.
After posting numbers on par with the some of the top starters in the National League for half a season, Guerra’s future with Milwaukee was suddenly clouded. Heading into arbitration eligibility for the first time in his career, Junior had to contend with not only his sudden struggles with his signature pitch, but his advanced age (he’ll pitch at 34 next season) as well as myriad promising homegrown arms already making a name for themselves in the big leagues. Pushed into a bullpen role, Guerra needed to use what few opportunities that may have presented themselves in September to prove to the powers that be that he was not only worth retaining for the next season, but that he deserved the significant salary increase that his pending arbitration case would put him in line for.
And that’s what he did.
Adversity is nothing new for Junior Guerra, who originally signed with the Braves as a catcher back in 2001 at the age of 16. He washed out as a position player at Class A when his bat failed to develop and was released by Atlanta in 2007. He signed with the Mets the following winter and in 2008, seven years after his professional career began, he made his debut on the mound in the low minors. He was released the following summer in 2009, though, after a failed PED test. That began an odyssey that took Guerra and his family all over the world in search of work as a pitcher, including stops in Spain, Venezuela, and the American independent ball circuits. He was pitching in Italy when he caught the eye of a scout from the White Sox, and on October 14th, 2014, Guerra punched his ticket back into affiliated ball by signing a minor league deal with Chicago for the 2015 season.
Guerra put up some eye-popping in AA and AAA for the White Sox around a three appearance, four-inning stint in the big leagues with Chicago, his first opportunity at the game’s highest level some 14 years after beginning his pro career. His work caught the eye of young David Stearns, and on October 7th, 2015, the newly-installed GM of the Milwaukee Brewers made Guerra the first acquisition of his tenure by claiming him off of waivers.
Guerra has looked the part of an ace before during his three seasons with the Brewers, winning the org’s Most Valuable Pitcher award in 2016 after posting a 2.81 ERA in 121.2 innings as a rookie to earn the Opening Day nod in 2017. But from the start of this September on forward, Guerra’s approach was one that departed radically from the heavy fastball-splitter combination that he had become known for.
During his final start of the year, against Washington on September 2nd, Guerra debuted a new pitch. Never before in Guerra’s career had he thrown a pitch that registered as a curveball according to Brooks Baseball, but of the 58 pitches he threw that day, 23 of them were curves. The new pitch averaged between 82-83 MPH and featured nearly 5 more inches of downward break than the slider he previously featured as his breaking ball.
Prior to September 1st, Guerra’s pitch mix had been 39% four-seam / 31% sinker / 13% slider / 17% splitter. After September 2nd, including six appearances to conclude the regular season and two playoff outings, Guerra’s revamped arsenal was 34% four-seam / 15% sinker / 9% splitter / 42% curveball. Junior threw 190 pitches in those eight appearances, and 80 of them were his brand new pitch. Batters hit .046 against the pitch - 1-for-22 - with 12 of those at-bats ending in a strikeout. Junior induced a healthy 15% swing-and-miss rate with his curveball, and on a per-swing basis, his 42.11% whiff/swing rate ranked among the top 15% of the 295 hurlers that spun at least 50 curveballs in 2018.
Junior Guerra's nasty curveball to strikeout Max Muncy pic.twitter.com/yr3JrIkdPj— Pitcher List (@PitcherList) October 17, 2018
The advent of Guerra’s spinner allowed him to effectively shelve his show-me slider, an ineffective offering that opposing batters torched for a .292 average and .462 slugging percentage in 2018. It also permitted Guerra to shift his split-finger to his third pitch, something he can save for when a two-strike pitch in the dirt is needed. The splitter was still effective overall in 2018, with batters hitting a mere .150 against the offering, but the pitch is thought be tough on the arm and by the end a the season in which Guerra dealt with arm soreness, it was clear that he was searching for a feel with it. Now, he had legitimately elite offering to rely on; according to data from Pitch Info, only three pitchers in baseball (min. 50 IP) had curveballs that graded higher in terms of runs above average on a per-pitch basis than Junior Guerra.
Junior’s first appearance out of the bullpen came on September 11th, and he concluded the regular season by making five scoreless appearances covering six innings. Only three of the 20 batters he faced recorded hits, and Junior issued zero free passes. He struck out eight. Finishing with a flourish was enough to convince Craig Counsell to keep Guerra on the playoff roster, ahead of guys like Chase Anderson and Zach Davies. Junior didn’t find action during the NLDS sweep against Colorado, but was called upon twice in the championship series against Los Angeles. He tossed a scoreless ninth inning in his postseason debut in the game two loss, then pitched 3.2 epic innings of relief during the 13-inning marathon that was game four, getting stuck with a hard-luck loss in extras despite allowing only two hits and one run with four strikeouts.
Guerra continued his successful reinvention in the Land of the Rising Sun, making two starts for the MLB All-Star Team during the Japan Series against that county’s national team, Samurai Japan. The All-Stars were defeated by Samurai Japan in the series, but that can hardly be pinned on Guerra; he tossed 9.1 innings with a 3.86 ERA in two starts with 12 strikeouts against five walks, and departed both starts with his team leading only to watch the bullpen falter late.
This past Friday was the deadline for MLB teams to tender contracts to their arbitration-eligible players, and among those that the Milwaukee Brewers elected to retain for the 2019 season was Junior Guerra. Our hero - and one baseball’s most inspiring working class heroes - is projected to receive a $2.7 mil salary via MLB Trade Rumors; at age 34 and after 18 years in professional baseball, that sum would be close to double what Guerra has earned to this point in his career. We don’t know exactly what role Junior Guerra will play in the Menomonee Valley next season; maybe he reports to Spring Training as rotation depth, or perhaps he becomes a right-handed compliment to Josh Hader as a middle-innings fireman. What we do know is that Guerra will be getting outs at the big league level for the Milwaukee Brewers, and that his new, potentially elite curveball may give him previously unforeseen upside heading into 2019.
Statistics courtesy of Fangraphs and Brooks Baseball