Three things we learned in the Celtics’ 120-107 loss in the season-opener at Miami on Tuesday:

No defense for that

Perhaps the one area where the Celts will struggle as they mix in new faces is on defense. Or perhaps the reason that the Heat could score at will was just because they are the Heat. Either way, it was far from a shutdown performance for the C’s, who allowed the hosts to shoot 54.4 percent from the floor. Transition D was an issue and Boston did a poor job of rotating and guarding the perimeter; the Heat buried 8-of-16 3-pointers and had a handful of gimmes. To put it in perspective, the Celtics allowed 120 points just once in 2011-12. They are on pace to do so 82 times in 2012-13.

Second unit will need a second chance

Or a third. Or a fourth. Or however long it takes to jell the way Boston fans hope it will. The mix of new players is very intriguing but it will not yield instant results off the bench. These things take time, as evidenced by some sloppy play by Jason Terry and company in the second quarter. As the subs sprinkled onto the floor, the Heat turned an early deficit into a nine-point lead. Soon after some Celtics starters returned, it was tied. Leandro Barbosa had a nice surge in the fourth, but Terry and Jeff Green were a combined 2-for-11 with four turnovers.

Speaking of Barbosa

In addition to Paul Pierce (23 points) and Rajon Rondo (20 points, 13 assists), the bright spot for Boston was Barbosa, who was the catalyst in a late run that fell short. The former Phoenix Suns star had all 16 of his points in the final quarter while making three of his four 3-point tries. This will change from game to game depending on matchups, but it is notable that Barbosa was the lone bench player on the floor for the Celtics during crunch time.


The Truth? The constant

At times in the first half, Paul Pierce, now in his 15th season, was the only thing the Celtics had going. He also continued a strong preseason trend with effectiveness behind the arc. Including his final four preseason games, Pierce has made 14 of his last 21 3-point attempts. The last time a Celtics roster did not include Ray Allen (2006-07), Pierce chucked up a bunch of 3s. That had more to do with the fact that he was on a crap team often playing from behind, but we may see a similar scenario as the captain does his part to fill a void.