The Celtics are 12-4 on the season; but to be honest, that’s not good enough. Not when three of those losses have come against the Cavs, Raptors and the Kevin Durant-less Thunder.

The C’s avenged the loss to Toronto, defeating them at home last Friday. They have a chance to do the same to Cleveland tonight when they travel west for Round 2.

Boston dropped countless games last season to teams they should have easily handled, so it wasn’t like coach Doc Rivers learned anything new during their loss in the second game of this season.

“Something that I know about every team — they can all beat you,” Rivers said. “They’re going to play hard against us every night; everyone is. … If you don’t come with the right focus you can lose any night. I think we’ve done a good job proving that this year.”

Coming off that big opening night win in Miami, the Celtics couldn’t get in the right state of mind to play Cleveland on a one-day turnaround.

“Just not going in the game with the mentality of finishing and destroying the team,” forward Glen Davis said. “We didn’t destroy them. We played a tough team the night before, and I think we were still in Miami, thinking about the Miami game, and we didn’t come to play the way we should have played.”

The Cavs are faced with a similar situation; perhaps they’re thinking about Miami, too. Just two days from now, LeBron James will play in Cleveland for the first time as a member of the Heat.

You can bet all of Cleveland will be watching that one — and booing.

“There should be a standing ovation and say, ‘Thank you for the seven years,’ but I have a feeling it won’t be that,” Rivers said of James’ return.