NBA'S Kelly Olynyk Hates Crappy Fantasy Owners ... Rips TMZ Photog

Nothing pisses off Kelly Olynyk more than a poorly run fantasy basketball league -- which is why the Boston Celtics player tore our TMZ photog a new one right in the middle of the street.

Long story short ... our guy is in a league that starts the fantasy playoffs THIS WEEK. Olynyk feels that's wayyyyy too early. He's right.

When our guy tried to explain why (in case NBA playoff-bound teams sit their stars at the end of the regular season) ... Kelly called B.S. and called for the commish to be FIRED.