5:57 AM PT -- Bauer claims MLB officials put a stop to his cleat plans almost immediately after he unveiled the kicks ... and the Reds ace was NOT happy about it.
The 29-year-old says the league threatened to eject him if he took the mound in the spikes ... and claims MLB even told him it might suspend him and/or levy "unprecedented fines."
Bauer says it's really unfair -- given MLB has a relaxed cleat policy for the 2020 shortened season -- and he went after commish Rob Manfredover it all late Wednesday night.
"Apparently, Rob is not a fan of players following his rules, as 'Free Joe Kelly' is not political and is very clearly said in jest," Bauer said.
"Just leaves me over here wondering how following the rules = ejection/suspension/fine and cheating your way to a World Series = no ejection/suspension/fine...y’all really know how to pick your battles..."
Trevor added, "learned my lesson though. Fun is bad, cheating is good. Won’t make the same mistake twice, can promise you that."
The cleat controversy clearly didn't bother Bauer's pitching arm ... even though he ultimately sported generic black Nikes on the bump vs. the Royals, he threw a 1-hit complete game with 9 strikeouts!!
Reds star Trevor Bauer is taking his support for Joe Kelly to his feet ... rockin' "Free Joe Kelly" cleats for Cincy's game Wednesday -- and the tribute is pretty amazing!!
As we previously reported, Kelly is set to undergo a 5-game suspension as soon as he comes off the Dodgers' injured list ... and it's all because MLB says he threw at cheating Houston Astros players last month.
But, dozens of guys in The Show -- including Kelly himself -- think it's all BS ... saying Joe didn't actually hit anybody, and he really wasn't involved in the near brawl on the field either.
Enter, Bauer ... who hates the Astros so much and is so firmly in Kelly's corner on the situation -- he had custom Joe Kelly cleats made for his start against the K.C. Royals!!!
TB showed off the footwear just hours before he took the bump ... and on the left shoe, Bauer had Kelly's infamous mocking face painted over the Nike swoosh.
On the right shoe, Bauer had the words "Free Joe Kelly" scribbled over the emblem.
"FREE JOE KELLY!" Bauer said along with the cleat announcement.
Trevor's support for Joe went one step even further ... the Cincy ace also made shirts for Kelly -- and says the proceeds from the tees will go to a charity of Joe's choice.