Will Marcus Smart play again this season? Celtics 'just don't know'

Credit: AP photoAs Marcus Smart seeks a second opinion on his sprained right thumb, the Celtics wait for news of whether their valuable stopper will play again this season.

According to a league source, the team literally has no idea of Smart’s probability of return.

“(They're) waiting for that second opinion,” a league source said today. “Don't know if it's a 50 percent chance or a 30 percent chance. Just don't know."

Smart hit the floor often during the Celtics’ Sunday night loss to Indiana, but one first half battle for the ball in particular had a foreboding effect in the form of a jammed thumb. After getting his thumb checked by trainer Art Horne, Smart returned to notch 20 points, seven…