Kansas City Royals reliever Lucas Erceg made a great first impression with the team in 2o24. The right-handed reliever was acquired at the trade deadline from the then Oakland Athletics and immediately became the most important bullpen piece for Matt Quatraro. In 25 innings after joining the Royals, Erceg posted a 1.17 FIP, striking out 31 batters while only walking three.
Erceg saved 11 games with the Royals in 2024, and at the start of 2025, he seemed like the obvious candidate to be the closer
for the Royals. The front office, after not being able to reach a deal for an outfielder, pivoted to signing Carlos Estevez and made him the closer. That freed up Erceg to be the team’s top setup man and fireman, depending on the game state. Although Erceg would go on to pitch the majority of the time in the eighth inning, Quatraro would not be afraid to bring him in the seventh inning or the ninth inning, depending on the matchup.
There was certainly discussions from Royals fans about whether it made sense to have Erceg in a firman role versus a more set role like a closer. The team’s legendary HDH bullpen featured guys in their set roles, and Ned Yost was a believer in guys knowing when they would come in. Quatraro, meanwhile, wants his guys to be more flexible in when they could appear. There was a bullpen pecking order, but Erceg needed to be ready to come in before or after the eighth inning depending on what batters were coming to the plate and how high the leverage was.
So what was the verdict for 2025? Was using Erceg in the more flexible role the correct choice? Should he have been locked in to the eighth inning, or even the closer? It’s hard to argue that Erceg would have been a better closer than Estevez, who racked up 42 saves with a 2.45 ERA. It’s also hard to argue with Erceg’s 2.64 ERA over 61.1 innings pitched. The job of a pitcher and their defense is to keep runs off the board, and Erceg did that consistently over the 2025 season.
Erceg’s 2.64 ERA is stellar, but his 3.49 FIP and 3.75 xERA suggest that he benefitted from some good variance. Watching Erceg this season was a different experience as well. I was happy to see him come into the game, but to my amateur eye he had to labor more to get good results compared to last season, when he looked unhittable. The biggest change in Erceg’s statistics from 2024 was a drop in strikeout rate. The reliever posted a 11.2 K/9 in 2024, but only had 7 K/9 in 2025. That is a pretty noteworthy drop. Erceg doesn’t owe anyone an apology for his ERA this year, but it’s difficult to remain a top reliever if you don’t strike a bunch of guys out.
Some of the drop in strikeouts looks like it could be a conscious choice to throw more strikes and live with the results. Erceg posted a career-high 52% groundball percentage, which will help you keep some runs off the board, especially with Gold Glove caliber defense on the left side of the infield. Even with the elevated groundball rate, I’m sure Erceg and the Royals wanted him to strike out more batters this year. So what changed from 2024 to 2025 that led to the drop in strikeouts?
I don’t have a definitive answer to what exactly led to the change in results, but we can still look back and make some educated guesses. Erceg this season struggled more with right handed hitters, allowing a .762 OPS against righties versus a .539 OPS allowed against lefties. Against right-handed batters, Erceg is more of a sinker/slider pitcher, and against lefties Erceg uses his four seam and changeup much more, along with the slider. The reliever struggled to miss bats this season with his sinker; he had a 8.7% whiff percentage with his sinker compared to a 21% whiff percentage with his sinker last year. The increased contact on the sinker would help explain the increase groundball rate, and some of those groundballs are going to get through as hits.
Erceg also didn’t get nearly as many strikeouts with his slider this season, despite a similar whiff percentage. He had a 37.5 whiff percentage on his slider in 2024, which led to a stellar 45.8 K% on that pitch. His whiff percentage on his slider in 2025 was 36.2%, but the subsequent K% was only 21.5%. Some of the difference is likely variation, relievers live in the land of small sample sizes, but I also wonder if Erceg and the Royals can alter his pitch sequencing to get more strikeouts with his slider. He doesn’t want to get too predictable, but if the slider is going to be his best swing and miss pitch, then trying to use that pitch to get punchouts seems like it could help him remain a top shelf set-up man.
Also, if you want the Royals to return to having pitchers in their set innings, Erceg was the most effective pitching in the eighth inning (.569 OPS allowed) compared to the seventh (.816 OPS allowed) or the ninth inning (.760 OPS allowed). The reliever only pitched 11.1 innings in the seventh and 8.1 innings in the ninth, so we are dealing with very small samples here, but his effectiveness coming in during a clean eighth inning versus coming in during a fireman role is something worth monitoring next year, assuming him and Estevez are both back next season.
Erceg also dealt went on the IL twice this season; once at the end of May with a strained lower back, and then again at the end of the season with shoulder impingement. Erceg was more effective in March-May than he was once he returned from his back injury; he had a 1.96 ERA before he went on the IL, compared to a 3.05 ERA the rest of the season. It’s certainly possible that Erceg was healthy enough to pitch and pitch effectively, but was still dealing with some injury issues that kept him from reaching his peak performance that we had seen the year before.
Off the field, Lucas Erceg let ESPN writer Jeff Passan join him for a talk that he gave at a prison in Boonville, MO about his personal sobriety story. It’s a great article and I appreciate that Erceg is willing to share his story publicly, both with the inmates and with the public at large.
Overall, Erceg was a key part of a Royals bullpen that 7th in the league in ERA. While I’m sure that both him and the Royals as a whole would like Erceg to get more strikeouts next season and would feel better about him at the back end of the bullpen if he finds them again, he was still an effective reliever in 2025 and helped the Royals finish above .500 for the second consecutive season.
