Cubs southpaw the surprise ace of last year's free-agent class

As the 22 teams that aren’t currently focused on capturing the 2024 World Series title gear up for the coming offseason, many will surely be keeping an eye on the number of high-profile free agent starters set to hit the market this winter with Corbin Burnes, Blake Snell, Max Fried and Jack Flaherty among the consensus top arms. It’s a class that’s not entirely dissimilar from last winter’s group of top arms, which was headlined by a quartet of Snell, Yoshinobu Yamamoto, Aaron Nola and Jordan Montgomery.

Those top free agent arms garnered a combined guarantee of more than $600M last winter, and the results were generally commensurate with that production. While Montgomery struggled badly with the Diamondbacks, Nola put up a fairly typical season by his standards with the Phillies this year (albeit with slightly diminished peripherals) and both Snell and Yamamoto fought through injury woes to dominate as expected when healthy. That said, a starter who was looked at more as a mid-rotation type of arm last winter surprised the baseball world by emerging with numbers comparable to those at the very top of the class.

That hurler was Cubs lefty Shota Imanaga, who was generally looked at as a tier below the aforementioned group alongside Eduardo Rodriguez, Lucas Giolito and Sonny Gray. In spite of rumors that Imanaga’s market could top $100M when all was said and done, the southpaw lingered in free agency into the new year before eventually signing with Chicago on a deal that fell far below expectations. While the deal maxes out at five years and $80M, just a stone’s throw away from MLBTR’s prediction of $85M over five years, the deal came with a complex structure that only guaranteed Imanaga $53M, or roughly two thirds of that $80M total figure.

It’s not hard to see why teams were seemingly bearish on Imanaga. After all, the 30-year-old lefty was coming over from Japan’s Nippon Professional Baseball at an age that’s roughly in line with a typical MLB free agent rather than the younger age many NPB players such as Yamamoto and teammate Seiya Suzuki make their way to the majors at. Yamamoto was marketing his age-25 season last year, while Suzuki marketed his age-27 season over the 2021-22 offseason. With many of Imanaga’s prime years already behind him, he maintained all the risk of providing a hefty sum to a player with no MLB experience without much of the perceived upside that would come with signing a player in their mid-20s.

Even aside from Imanaga’s age, it’s also worth noting that the lefty’s profile as a pitcher drew significant questions. The southpaw doesn’t throw especially hard, having averaged just 91.9mph on his heater this year, and some scouting reports (including one from Brandon Tew of Sports Info Solutions) raised questions about his ability to manage home runs at the big league level due to his fly ball-oriented profile. While Imanaga’s deep pitch mix and high-end stuff metrics offered reason for optimism regarding his future in the big leagues, the lefty nevertheless entered his first MLB season with plenty of questions surrounding him.

Fortunately for both Imanaga and the Cubs, he answered those questions in resounding fashion with an excellent rookie campaign. Overall, the lefty posted a 2.91 ERA (37% better than league average by ERA+) with a strong 25.1% strikeout rate that was 16th-best among qualified starters this year. He paired that strikeout stuff with excellent control, walking just 4% of opponents faced this year. That’s a figure topped by only George Kirby, Miles Mikolas and Zach Eflin among all big leaguers this year and leaves him with a fantastic 21% K-BB that leaves him sandwiched between ace righties Zack Wheeler and Dylan Cease on the NL leaderboard.

That being said, not everything about Imanaga’s 2024 performance was dominant. His 3.72 FIP is rather pedestrian (just 6% better than league average by FIP-) and more advanced metrics such as xERA and SIERA, while more bullish than FIP on his performance, nonetheless see him as more of a 3.50 ERA pitcher than the 2.91 figure he actually posted this year. The main culprit for that discrepancy between results and metrics is the very same weakness that drew some skepticism last winter: his proclivity for giving up homers. Imanaga surrendered 27 home runs this year, tied with Twins righty Bailey Ober for ninth-most among all qualified starters in 2024.

While that’s certainly not a completely untenable figure, it would certainly be fair to wonder if Imanaga is due for some regression heading into next season. Of the eight pitchers who surrendered more homers than Imanaga this year, none came close to his sterling ERA with only Nola (3.57) and Jose Berrios (3.60) posting an figure that was even within a full run of Imanaga’s 2.91 mark. Between his hefty home run rate and an above-average 80.2% strand rate this year, it would hardly be a surprise if the emergent ace put up numbers closer to the mid-rotation ceiling he was thought to have this time last year come 2025.

Of course, even a step back that aligns Imanaga’s performance more closely with his advanced metrics would leave the Cubs with an excellent No. 2 starter behind ace Justin Steele whom they should have no concerns about starting in a hypothetical playoff series. Barring dramatic regression on the part of Imanaga next year, it seems very likely that the Cubs will guarantee the lefty the full $80M value of his contract rather than risk him opting out following the 2025 campaign, which he would be able to do if the Cubs decline to guarantee the full contract.