J.R. Smith Made TWO Bonehead Plays, Says Charles Oakley

Charles Oakley says it wasn't just the last play of regulation that J.R. Smith screwed up Thursday night -- he also made a crucial mistake in the 1st half that cost his team 3 points ... and maybe the game.

Oak was pretty upset with Smith's decision to go for a steal instead of playing shutdown defense on Steph Curry in the final seconds of the 1st half.

Smith missed the interception and Steph bombed a 3 ... Oakley says that was a major momentum change.

"Why are you going for a steal on the best shooter in the game?!"

Oakley says he hopes the Cavs can recover and bounce back strong in Game 2.