How Brewers' World Series Game 3 starter Robert Gasser became a key postseason weapon

The Milwaukee Brewers take with them to Tropicana Field a 2-0 series lead in the World Series. Pat Murphy's squad has won seven consecutive games dating back to their victory over the San Diego Padres in Game 4 of the National League Division Series, and are hoping to keep that streak intact with southpaw Robert Gasser on the bump for Game 3 of the Fall Classic.

Gasser's rise to the Brewers' Game 3 starter in the franchise's first World Series appearance since 1982 was by no means typical. The 27-year-old left-hander, who technically still qualifies as a rookie due to the amount of time he's missed in each of the previous two seasons, wasn't viewed as one of the team's top rotation options for much of the 2026 campaign, but a strong finish to the season gave "Bobby Diesel," as Gasser is affectionately known by the Milwaukee faithful, the opportunity to leave his stamp on the Brewers' 2026 postseason run.

On August 20, following a 3.2-inning start against the Seattle Mariners in which he gave up four earned runs, Gasser held a 4.79 ERA and was seemingly the weak link of the Brewers' six-man rotation. In fact, had it not been for Milwaukee's decision to utilize a six-man rotation throughout the month of August, Gasser may not have kept his role in the starting rotation. However, in the time since that start against the Mariners, the rookie southpaw has proven that he not only belongs in the Brewers' rotation, but could be a key part of it for the foreseeable future.

Beginning with an appearance on August 26 against the New York Mets, in which he took over for Dustin May, who was struck with a comebacker in the top of the first inning, Gasser has been on the most effective streak of his young major-league career. In his final six outings of the regular season, which included his fill-in appearance for May in late August, Gasser posted a 1.67 ERA, with a 0.96 WHIP and a .165 opponent batting average. He covered 32.1 innings during those six appearances and struck out 24.0% of the batters he faced (up from the 21.6% strikeout rate he posted through his first 15 outings of the 2026 campaign).

As a result of his impressive final month of the regular season, Gasser was not only included on the Brewers' NLDS roster but ended up playing a prominent role in Milwaukee's defeat of the Padres. With his team sporting a 2-1 series lead, Gasser got the ball to start Game 4, and the low-slot lefty delivered four innings of one-run ball, with his lone blemish being a solo shot from Fernando Tatis Jr. in the third inning. The Brewers went on to win the game and advance to the NLCS, where Gasser's role in the rotation changed.

Due to Gasser's strong showing in Game 4 of the NLDS and May's lackluster start in Game 3, Murphy elected to move his rookie left-hander up to Game 3 in the Brewers' NLCS matchup with the Los Angeles Dodgers. Once again, Gasser delivered. He tossed five shutout innings against the Dodgers' star-studded lineup and left the game with a 1-0 lead that was initially squandered by the bullpen before the Brewers came back to win the game.

Now, Gasser is set to start Game 3 of the World Series, a reality that certainly felt unlikely back in mid-August. However, due to an increased effectiveness against right-handed hitters and slight changes to his pitch mix that have emphasized the offerings he feels most comfortable with, there's reason to believe Gasser's recent hot streak will continue in the Fall Classic.

Finding success against right-handed hitters has been key to Robert Gasser's late-season surge

Perhaps the biggest difference between Gasser's first 15 outings of the regular season and his final six was the southpaw's success against right-handed hitters. Before his late August inflection point, right-handed hitters were maintaining a .293 batting average, a .348 on-base percentage, and a .500 slugging percentage against Gasser. Righties had an average exit velocity of 88.1 mph and a hard-hit rate of 34.5%. However, in Gasser's final six appearances of the regular season, right-handed hitters maintained a .167 batting average, a .263 on-base percentage, and a .298 slugging percentage while posting an 85.8 mph average exit velocity and a 31.7% hard-hit rate.

That improved success against right-handers was undoubtedly a key part of Gasser's late-season effectiveness, but the reason why the left-hander improved against opposite-side hitters is less obvious. While one would assume that improved success against right-handers would mean that Gasser was relying more on his four-seam fastball, cutter, and changeup, pitch-tracking data suggests that his use of the four-seam and cutter against right-handers actually decreased during the final month of the season while his changeup use only moderately increased. Instead, Gasser increased his sinker and slider use (two offerings that should be more effective against lefties) when facing right-handed hitters during the final month of the regular season. That reliance on his sinker-slider combo when facing righties has only increased during his two starts in the postseason.

On Saturday afternoon, when asked what he believed is the reason for his increased effectiveness against right-handed hitters during the final weeks of the regular season and into the postseason, Gasser said, "Nothing in particular. Again, I trust William to call the pitches. I do my best to execute. Right now the sinker and the sweeper combo has been working well." The southpaw's comments reiterate the fact that despite his sinker and sweeper both having a negative run value against right-handers during the regular season, it's that combo that he feels most comfortable with against opposite-side hitters right now.

Perhaps the fact that Gasser is throwing the two pitches with confidence and conviction is enough to overlook the fact that his expected ERA against right-handers remained essentially unchanged after his late August turnaround. He's certainly locating the two pitches well in October, and did so down the stretch in the regular season as well, but it's nevertheless surprising just how well they are working against right-handers. Does that indicate regression is on the horizon, or will Gasser's seemingly inexplicable success against right-handers continue in the Fall Classic, in which he will face two incredibly talented righties: Yandy Díaz and Junior Caminero? Expect the changeup, which Gasser did make use of against Tatis and Manny Machado in the NLDS to be used against Tampa Bay's pair of righties, where Gasser's inconsistent ability to locate the pitch will once again take center stage.

There's no arguing with Gasser's late-season success, especially the improvements he's made against right-handed hitters. However, the inexplicable nature of those improvements could spark some minor concerns about Gasser's ability to continue his ongoing hot streak. The Brewers are certainly hoping Gasser's confidence in his sinker-slider combo will outweigh the fact that neither pitch was especially effective against right-handers during the regular season. Sometimes pitching with conviction is all that's required to out-perform underlying metrics.

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