There isn’t a game on the schedule where Eric Gordon doesn’t come in handy, but against Boston’s ball pressure in the halfcourt, EJ’s absence is especially costly. The Celtics’ defense focuses on cutting off large swaths of the floor with hard traps. The best way to alleviate that pressure? Perimeter spacing, something that can be achieved with a couple of lethal perimeter threats. Without a shooter like Gordon keeping the defense honest, the Celtics’ tighten their vise even further.

Chris Kaman doesn’t get so much as a touch until the fourth possession, as Boston’s big men deny him the simplest entry pass. He knocks down that first touch (1st, 9:45), but not before Perkins pushes him back with that big left hand, forcing Chris into an awkward fall-away. Kaman hits his second attempt as well (1st, 8:13) when Perkins absently blitzes Baron, with no one rotating on Chris.

After that, it’s a tough go. Kaman converts only three of his final 16 attempts and never sees the stripe.

Kendrick Perkins might be best known for his brawn, but he’s very cerebral with that physicality. Perk pushes his defensive assignment off his preferred spot, but more than anything, he wants that man to feel uncomfortable. He wants him to know that what little space he’s afforded comes at a premium and can be taken away without notice. When Baron and Kaman flirt with the pick-and-roll in the first quarter, Perkins dances between Kaman and Rondo, making sure that Chris isn’t able to initiate the action. At the same time, he’s watching for the slip, making sure that Kaman doesn’t pop out to open space for a quick dish and a clean look. When Chris has the ball one-on-one, it’s all pokes and hips from Perkins. Kevin Garnett picks up Kaman in transition (1st, 5:27), and stays in front of him throughout the possession, even after Davis slows it up to look for offense.

The Clippers can’t find much of it all night, and when there are rare opportunities to get easy scores, the Clippers’ shpilkes get the better of them. Desperate to get anything in transition — because nothing is working in the halfcourt — the Clips overthrow an outlet pass on a potential break on four separate occasions. These aren’t instances of random carelessness; they’re the direct result of the Celtics’ defense. For a while, it looks like the Clips might go to that old standby: Baron Davis in the post against a smaller opposing point guard. Tonight, the Celtics are ready and send quick help when Baron begins his assault on Rajon Rondo.

Somehow, despite the poor shooting, the Clippers are able to build a lead in the second quarter and hang around until the bitter end. Again, it’s the second unit led by Mardy Collins, Ricky Davis and Craig Smith that empowers the Clippers. You see it on their first defensive possession of the second quarter (2nd, 11:05). They buzz around the halfcourt, talking to one another and pointing to primary defensive assignments who are being vacated for double-teams. They contest every pass and shot. It certainly helps that Rasheed Wallace takes all the 3-point attempts he can eat and that Boston has not one legitimate passer in their reserve unit, but the Clippers’ activity is unmatched and it ignites a 16-7 run to give the Clippers an eight-point lead (nine was their largest). When the Celtics appear like they might run away with the game in the fourth, the backups come through again. Smith bullies Perkins one-on-one on the offensive end and the unit again communicates well on the defensive end. You see it at (4th, 9:07) when an early, high screen from Wallace yields a mismatch for Rondo in DeAndre Jordan. As Rondo lures DJ out to the perimeter to prepare to carve him off the dribble, Ricky Davis dashes over to help while the rest of the defense rotates. It’s a high-quality brand of basketball from some very improbable sources.

The defining stretch of the game, though, is the outset of the second half, when the Clippers are stifled by the Celtics’ energized halfcourt defense. The Celtics do more than just push the Clippers out. You’ll see Paul Pierce double Kaman off the ball underneath on the weak side (3rd, 11:08). You’ll see the Celtics send Garnett to pick up Chris on a Baron-Kaman screen (3rd, 8:05), with Perkins staying on Baron and Rondo free to rove passing lanes. As the ball works its way over to one side of the floor, the Celtics follow it, strangling the Clippers and inducing flaming bag (3rd, 7:51) after flaming bag (3rd, 7:05) at the shot clock buzzer. Pressure like this can be combated by quick reversals to good shooters, but the Clippers don’t establish any semblance of an outside game until the interminable closing minute when, in desperation, they drain three 3-pointers. Even with the late heroics, it’s never more than a two-possession game.

Though the contest never gets out of the Clippers’ reach, it’s never in their grasp either. Somehow, that 4-to-10 point lead the Celtics nurse most of the second half seems insurmountable.