TJ Stuff: Yoshinobu's Story
Yoshinobu Yamamoto, Spencer Schwellenbach
Welcome to “TJ Stuff”, a series which aims to highlight any intriguing MLB players and performances.
Swift Stuff
Jesus Luzardo keeps throwing his new sweeper which continues to stump LHH.
Tylor Megill expanded his shrunken arsenal by reintroducing his curveball and changeup. Both the curveball and changeup are ~3 MPH harder with more movement than last season.
Shota Imanaga’s fastball velocity averaged 90.3 MPH yesterday, ~2 MPH slower than his previous outings. Something to keep an eye on.
Max Meyer’s revamped arsenal keeps chugging along. The slider is still elite and the added velocity on his fastball makes it a much more formidable offering.
Yoshinobu Yamamoto
Yoshinobu Yamamoto has gotten off to a hot start this season, posting a nice 1.69 ERA and 3.23 FIP across 16.0 IP. The Japanese ace is showing improved velocity and pitch shapes in the early going which bode well for his future production. The biggest knock against Yamamoto in his rookie season was his below average fastball shape. The offering returning poor whiff rates and was consistently hit hard. Through his 3 starts in 2025, his fastball is averaging +1” iVB with a very slight velocity bump. This change helped raise its tjStuff+ from 96 to 105 and its results have agreed. Given his tendency to locate the pitch to the outer third rather than higher in the zone, I expect Yamamoto’s Whiff% on his fastball to be below average. The new shape should help mitigate damage.
Yamamoto is also throwing his splitter harder. It ups +1.6 MPH which exhibiting more depth and arm-side ride. tjStuff+ agrees that this is a positive change (103 to 107), and its blazing 57.1 Whiff% makes it difficult to refute. Another tweak that looks encouraging is his cutter getting ~3” more glove-side action.
Overall, Yamamoto is generating a lot more whiffs while limiting damage. His improved stuff meshes beautifully with his pinpoint command to create one of the most complete pitchers in baseball!
Spencer Schwellenbach
Picture Yamamoto and essentially clone him and put him on Atlanta, and boom, you have Spencer Schwellenbach. Ok, the comparison isn’t perfect, but they wield a similar arsenal and have excellent command while making notable adjustments this season to reach that next level.
Schwellenbach is an artist. He wields a true 6 pitch arsenal that he mixes and matches to handle any kind of batter. This ability is easily explained by his fastball usage. This season he increased his 4-Seam usage to 41.6% vs LHH while slashing its usage to just 10% vs LHH. To balance out these changes, Schwellenbach has passed out his sinker vs LHH (0%) while making it his primary fastball vs RHH (34.4%).
Schwellenbach has also exhibited a modest improvement of his stuff, the most prominent being his fastballs, again. His 4-Seam graded out at 100 tjStuff+ in 2024, making it decidedly average. In the early going, he added 2.5” iVB while maintaining its other attributes to improve its score to a strong 108 tjStuff+. His sinker is showing +1.5” of arm-side run with a slight uptick in velocity. These changes elevated its tjStuff+ from 95 to 101.
Schwellenbach is a budding star. Everything from his deep arsenal, elite command, smart usage, and improving stuff essentially proves it. He will be a treat to witness what he will develop into this season!
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