On August 16, with the Mets reeling after losing 13 of their last 15 games, they turned to top prospect Nolan McLean for a spark. The rookie responded with 5 1/3 scoreless innings, striking out eight against a tough Seattle Mariners lineup. The Mets went on to win 3-1.
Before making his MLB debut, the 2025 season had already been a resounding success for McLean. Drafted in the third round in 2023 as a two-way player out of Oklahoma State, he shifted to pitching full-time in July 2024, hoping to fast-track his development by focusing solely on the mound.
And fast-track he did. McLean carved through Double-A Binghamton, posting a 1.37 ERA across 26 1/3 innings before a quick promotion to Triple-A Syracuse. There, he continued to impress, striking out 97 across 87 1/3 innings with a 2.78 ERA in the hitter-friendly International League.
His dominance at the upper levels turned McLean into one of the fastest risers in baseball. He opened 2025 ranked No. 99 on Baseball America’s Top 100 list, but has since climbed to No. 39, making him the Mets’ top pitching prospect. MLB Pipeline echoed that rise, bumping him from unranked in the preseason to No. 36 overall.
The Mets announced McLean would stay in the rotation after his debut against Seattle, and he’s rewarded that decision ever since. In his second start, he went seven innings in Atlanta against the Braves, allowing two runs and striking out seven, becoming the first Mets pitcher other than David Peterson to complete six innings since June 7. He followed that with his most dominant outing yet: eight scoreless innings against the Philadelphia Phillies, making him just the second Mets starter (alongside Peterson) to pitch into the eighth this season. Most recently, McLean logged six innings of two-run ball against the AL-best Detroit Tigers. The Mets are 4-0 in his starts, with McLean earning the win in all four.
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While the sample size is small, both the on-field and underlying metrics are encouraging for McLean. He’s already shown a six-pitch arsenal: four-seamer, sinker, cutter, changeup, sweeper and curveball.
Against righties, McLean leans heavily on his sweeper and sinker, each making up about a third of his pitches, with the four-seamer (18.6%) and curveball (12.2%) rounding out the mix. He’s barely shown his changeup and cutter, throwing just two of each. The results have been impressive: righties are 6-for-40 (.150) with zero walks and 13 strikeouts. The sinker has stood out as his most effective weapon, with hitters going 2-for-17 with four strikeouts against it.
Against lefties, the distribution is more balanced. The sweeper (24.3%) and sinker (22%) still lead the way, but he mixes in more curveballs (20.1%) and incorporates his cutter and changeup roughly 10% of the time each. Left-handed batters are 7-for-47 (.149) so far with no extra-base hits and 15 strikeouts. McLean’s curveball, boasting a MLB-best 3,267 RPM, has been a particularly potent put-away pitch, generating seven strikeouts in 12 plate appearances where it was the final pitch. His changeup has also been effective, recording four strikeouts in 12 opportunities while allowing no hits.
While McLean can’t be expected to sustain a 1.37 ERA all season, his expected metrics suggest he can continue pitching at a high level even with some regression. Using Baseball Savant’s filters, we can see where he stacks up despite a small sample. Among all pitchers with at least 50 balls in play this year, McLean ranks No. 11 in expected batting average against (xBA) at .193 – that’s the third-best among starters, behind only Milwaukee’s Brandon Woodruff and Jacob Misiorowski.
The quality of contact against him has been just as impressive. His expected slugging percentage against (xSLG) sits at .301, ranking No. 13 overall while representing the best mark among starting pitchers. His expected weighted on-base average (xwOBA), which factors in strikeouts and walks in addition to contact, is .252 – placing ninth overall and again coming in as the top mark among starters. By expected ERA (xERA), McLean also leads all starting pitchers at 2.45.
McLean’s first handful of weeks in the majors have shown why the Mets were so high on him. From dominant outings to an advanced pitch mix and elite underlying metrics, he’s proven himself capable of competing at the highest level. While his big-league career is still in its infancy and some regression is inevitable, McLean has quickly established himself as not just a promising prospect, but a potential ace in the Mets’ rotation for 2025 and beyond.
