Check out some photos of the New York star while he was vacationing in Miami Beach over the weekend ... you can see he wasn't shy about puffin' on what appeared to be a joint while downing a Casamigos-fueled cocktail.

Wearing nothing but some board shorts, he sprawled out on a luxury resort's lounge chair ... and flashed a big grin as he sipped his drink and blew out swathes of smoke. Remember, the MLB removed marijuana from its banned substance list years ago, so no problems with Rob Manfred here if that's what it is.

Chisholm was also surrounded by some happy ladies too -- showing that the pain of losing October's Fall Classic to the Dodgers might finally be subsiding.

Of course, the scene was completely different back on Oct. 30 -- after L.A. won the MLB's championship over Jazz's Pinstripes in five games.

Chisholm had expressed some big confidence before the Game 5 defeat that New York could pull off an improbable come-from-behind win ... but when the Yanks couldn't get it done, he wasn't thrilled, to say the least.

Chisholm, though, hasn't gone into hiding since the L -- he's actually been spotted at a few Knicks games throughout November.