Even with the barrage of 3s from Dallas in overtime Monday night and the increasing number of teams that are scoring 100-plus points against Boston, the Celtics defense is still pretty good.

But there is no denying there has been some slippage of late even in victory, which will be among the team’s chief concerns heading into Wednesday night’s game at Toronto.

In the 118-113 overtime loss at Dallas on Monday, the Celtics gave up a season-high 16 made 3-pointers with four coming in overtime which factored into another high-scoring game for Boston (22-20).

Before December 31, Boston had allowed opponents to score 100 or more points just 13 times in 32 games. During that stretch, the Celtics never gave up 100 or more points in three consecutive games.

The narrative has changed dramatically when the calendar flipped to 2016.

In the 10 games Boston has played this month, the Celtics have allowed 100 or more points seven times which includes a pair of three-game stretches in which they allowed 100-plus points.

Boston is still playing good defense, evident by their current defensive rating (points allowed per 100 possessions) being 98.8 which is the second-best in the NBA to the San Antonio Spurs (93.3).

But if you look at their last four games, Boston’s defensive rating (101.5) slips down to eighth-best in the NBA despite winning three of those games.

Part of the slippage defensively has to do with the use of smaller lineups for longer stretches lately.

While there is no mistaking the fact that head coach Brad Stevens’ decision to play with smaller units for longer stretches has helped win games, it does have its flaws which we saw the Dallas Mavericks do as good a job as anyone this season in exploiting.

There were a number of offensive series where the Mavericks had a decisive matchup in their favor, like when Dallas would run some pick-and-roll action which left 5-foot-9 Isaiah Thomas out near the free throw line having to defend 7-foot Dirk Nowitzki or created an isolation situation for one of Boston’s big men and one of Dallas’ guards.

Stevens said the Celtics have to play a certain way when they are in small-ball mode, and that didn’t happen enough against the Mavericks.

“When we go small which is something that we’re just going to have to figure out, we’re going to have to be awfully aggressive and active and close to the ball,” Stevens told reporters after Monday’s loss. “Otherwise we’re not going to impact it. If we’re not impacting it, deflecting some of those passes, we’re not going to look big closing out. And so we need to make sure we’re better than that. It’s easier said than done.”