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By Bat Digest
Updated August 10, 2023
Our hitters loved the exit speeds. The feel on the bat was good, but nothing to write home about. If you hit one off the end cap, you for sure felt it. But, that's the type of feedback some players prefer. In terms of straight exit speeds and overall performance in BBCOR, the B21 performed like highly recommended Rock Star.
It swings on the heavier side. Of all the 33-inch bats we measured in swing weight for 2020, the 9500 score on the B21 puts it in the top 5 of heavy swing weights. (We realize this is a 2021 bat, but at the time of release, it was one of the only 2021s around. So, our reference point, for now, is in the 2020 swing weight realm). In as much as it is a heavier swinging bat, and the fit is just about everything in BBCOR bats, do know you are getting one that's a bit more difficult to swing than you might hope. See our full list of BBCOR bat swing weights here.
Compared to the 2020 Mizuno Hot Metal, there have not been a lot of changes. It is still a single piece aluminum bat with a big barrel and end load. Expect similar feel too. In either case, expect big hits if you can handle it.
The Mizuno B21 Hot Metal is a single-piece aluminum bat made from a single wall of aluminum. The bat wall adjusts it's thickness as it moves from the center of the bat to its outsides. This helps increase bat performance outside of the dead center of the bat. Several companies, including the CAT 8 from Marucci and Velo from Rawlings, use a similar tactic.
B20-HOT METAL BBCOR Baseball Bat combines Mizuno’s powerful HotMetal™ single-wall aluminum alloy with innovative CorTech™ technology, which adjusts wall thickness across the barrel to create a high-performance bat with an aggressive sweet spot. Engineered details like an Optimized End Cap create a booming sound, while also increasing the size of the sweet spot to give you the hottest one-piece bat in the game. (source)