It takes guts and heart and conditioning to play defense.
For a bunch of role players and castoffs to play defense the way the Sixers have played it lately is, frankly, insulting.
It speaks of entitlement. With 15 wins in 50 games, this team is barely entitled to a plane ride to the next city.
Let them "Go Greyhound" for a few days. See whether the defensive intensity doesn't improve.
It is driving coach Brett Brown crazy.
"It's something I have to wear. I have to fix it. I have to inspire these guys to better understand the importance of it," Brown said. "Anything related to defense is something that stings deeply.
He repeated, for effect:
"It stings, deeply."
Brown might be right in that, often, effort reflects atmosphere, and coaching creates atmosphere.
Brown might be wrong, though, when he contends that his primary players lack the athleticism to stay with a given team, especially when that team is Boston.
The Sixers forced seven turnovers in the final 6 minutes, 19 seconds. They played with a pace and intensity that would help them contend with any team in the league, if only they played that way for more than a minute or 2 at a time.
Clearly, Brown needs to better communicate this to his players.
"I don't think it was a matter of defensive intensity," Evan Turner said. "They made jump shots and threes. They made the shots we wanted them to take."
Turner, a fourth-year player, leads the team in points and, significantly, in minutes.
Perhaps reflective of Turner's mindset, the Sixers have allowed opponents to shoot better than the league average of 45.1 percent from the field in eight of their last 14 games.
They are 1-7 in those eight games.
Last night's defensive disconnect wasted a fine effort from enigmatic big men Spencer Hawes and Lavoy Allen, who combined for 24 rebounds and 23 points. They generally were not the issue.
Perimeter defensive effort and transitional defensive effort were the problems.
Avery Bradley hit a wide-open jump shot at the back of the Sixers' press, mainly because the players at the front of the press declined to get back.
Brandon Bass downed a two-handed dunk, because, inexplicably, Allen cheated toward the top of the key to help a teammate who had yet to be beaten.
Tony Wroten showed little urgency in pursuing Bradley, which led to another easy jumper, then failed to reverse quickly enough to follow Bradley over a screen, which led to two free throws for Bradley.
Those two points put the Celtics up, 29-21, with a little more than 2 minutes to play in the first quarter. At that point, they had shot 70 percent from the field.
"In the first half, in transition defense, especially, it was poor," Brown noted.
It was not a gamelong issue, because it was defense that kept it close.
Allen bullied three Celtics for an offensive rebound and put-back, then rushed downcourt and broke up a long pass to Jared Sullinger, which led to a Michael Carter-Williams layup.
That series of plays cut the Celtics' lead to 73-67 with 5:32 to play in the third quarter.
That series of plays should be routine, regardless of the opponent.
It is a symptom of the times, perhaps.
Nobody becomes an NBA lottery pick because he consistently gets his hand in the face of a jump shooter, then boxes out.
Nobody gets on "SportsCenter" for moving his feet and denying passing lanes (just ask Shane Battier). Moving your feet and denying passing lanes are trademarks of all decent teams (just ask Shane Battier).
The Sixers are not, repeat not, incapable.
Consider their second quarter, when the Celts shot a little less than 43 percent.
Rotations got a little bit quicker. Defenders became a bit more committed. For instance, Young, the team's best player this season, was the reason Bass flushed a second dunk in the first quarter, because Young didn't hustle back on defense.
In the second quarter, on consecutive Celtics possession, Young fouled Jeff Green instead of allowing an easy layup, then rotated a full step quicker and blocked Green's shot.
A couple of possessions later, Wroten was actually on all fours in pursuit of Rondo, with whom Wroten was charged with denying the ball. Rondo did not touch it.
If Jeff Green is going to rock a thunderous back-pick alley-oop from Rondo, then drop a contested three in Turner's face on consecutive possessions, so be it.
Bass is going to hit a jump shot or two over Hawes; it is the nature of that matchup.
Carter-Williams dribbled the ball off his foot with 25.5 seconds left. You live with that.
On Twitter: @inkstainedretch