UFC Champ Stipe Miocic -- SMACKS HOME RUN ... at MLB Ballpark (VIDEO)

Here's UFC heavyweight champ Stipe Miocic belting a home run out of Progressive Field in Cleveland earlier today ... well, because he's a freak athlete.

Miocic was taking batting practice with the Cleveland Indians when he connected -- and blast the ball over the left field wall.

FYI, Miocic played college baseball at Cleveland State University ... but that was like 10 years ago.

#StillGotIt