HOUSTON — A team that has prided itself on defensive dominance over the past half-decade is now allowing reserves such as Houston’s Greg Smith and San Antonio’s Tiago Splitter to record career nights. This is what the Celtics’ once-proud and pristine defense has been reduced to.

Opposing teams are spending games going after the Celtics’ rotating defense, realizing one of the five guys is going to shift a half-second late. It happened all night Friday at the Toyota Center, as mastermind Kevin McHale, who used to overwhelm defenses with his post game, challenged the Celtics to stop Houston’s bigs near the basket.