Players have had customized bats for a very long time - wood type, weight and even some on how it's distributed.
This just cranks that up a bit more.
Other players/teams were using them last year. Stanton used one in the playoffs last year when he was launching everything, but it wasn't a conversation item because he has the ability to launch when he's actually playing
By all accounts the bats are legal. If they aren't snapping and becoming dangerous then go with it. If there becomes a noticeable increase in exit velocity for like players over s wide enough sample where it could put your more vulnerable IF positions as risk, then maybe it will need to be looked at.
I'm a marlins fan and the creator is a bench check for the marlins and they still stink
