Boston Celtics center Aron Baynes was downgraded to “out” against the Chicago Bulls, according to Brad Stevens. Baynes sprained his left ankle against the New York Knicks on Thursday. Stevens joked after the game that Baynes would insist he is healthy enough to play, but Stevens said he wasn’t sure the team’s doctors would agree. Stevens told reporters at the team’s shoot around that Baynes did progress. “He’s progressed really well, he did a lot yesterday, but just not quite ready to play,” Stevens said. Baynes played just two minutes against New York before taking a bad step rolling down the lane to the basket and twisting his ankle. He dropped to the floor immediately and went straight to the locker room when he finally struggled to his feet. The Celtics — who have a lot of depth at center with Al Horford, Daniel Theis and Robert Williams — won’t hurry Baynes back, especially for a game against a team like the Bulls. But with a Christmas Day contest against Joel Embiid and the Philadelphia 76ers looming, the fact that Baynes is progressing several weeks in advance is encouraging.