Stats glance: Celtics' offensive struggles

Monday’s loss dropped the Celtics to just 5-7 over their last 12 games, a disturbing trend for a team many have pegged all season long as the odds-on favorite in the top-heavy Eastern Conference. Since the All-Star break, Boston is just 11-8 and trails the Bulls (15-4 since the break) by 2 games for the top seed in the East.

If you may recall, the Celtics also struggled down the stretch last season, finishing 27-27, including an 18-14 mark after the All-Star break.

Since trading away Kendrick Perkins and acquiring less defensively inclined players such as Jeff Green, Nenad Krstic and Troy Murphy, one might think that the biggest difference between this year and last year's team was that the 2009-10 crew that made the NBA Finals was at least defending at a much higher level.

It appears that's not the case (see chart).

So if we're looking for differences between this year and last year in terms of why the Celtics have struggled down the stretch, we need to look at the other side of the ball.

Simply comparing the team before and after the All-Star break gives us a general idea that something is up. Before the break, the Celtics had an offensive rating (points per 100 possessions) over 105, which ranked near the middle of the pack in the NBA. For a team that plays at a slower pace and relies heavily on its defense, that efficiency enabled Boston to score 97.9 points per game ... nowhere near the top of the league but certainly good enough given its own strengths.

After the break, that offensive rating has dropped to 101.6, which has translated into an offense generating just 93.1 PPG, 27th-best in the NBA (only the Bucks, Hawks and Bobcats have been worse).

So why has the Celtics’ offense suddenly fallen off?

Prior to the break, the Celtics assisted on 64.5 percent of their made FGs, the best mark in the NBA. That number has since dropped to 61.8 percent. Two of the reasons for the teams’ plummeting assisted field goals? Rajon Rondo’s declining productivity and Boston’s suddenly cold outside shooting.

In the months of October and November, Rondo averaged 14.1 assists per game, which easily led the NBA. In March, that number has dipped all the way to 8.6. During the Celtics’ current 5-7 slide (of which Rondo has played in all but one game), he has reached double-digit assists just twice.

Why is that important? In games in which Rondo records at least 10 dimes, the Celtics are 32-6. When he falls short of that threshold, Boston’s record is just 11-12.

In the month of March, his PER (player efficiency rating) is a pedestrian 13.0. That is lower than such point guard luminaries as Jordan Farmar, Acie Law and Earl Boykins ... as in not the sort of production Doc Rivers needs from his All-Star point guard. Of course for those assist numbers to jump back up, his teammates need to start hitting some shots.

In the last 12 games, Boston has been horrendous from beyond the arc, connecting on just 42 of 139 3-point attempts, or 30.2 pct. Over the course of a season, 30.2 percent would be the worst mark in the league. Before this current stretch, the Celtics were hitting 37.4 percent from downtown, sixth in the NBA.