Celtics went 7-8 in December. Not very good given the strength of schedule but not outright horrible. Right now, they're probably on track to finish with a win total in the low 30s, which at worst is only a little under their talent-level.
As much as I would criticize him, Stevens appears to be competent. He is light years, however, from looking like the coaching genius Boston was supposed to be getting. There is reason to believe that he'll get better results when Ainge gets him better talent. I'm not sure that's what you want when you give a guy a 6 year deal for nearly $4 mil a year.
Mike