Paul Pierce and Kevin Garnett have cast a misleading image over the Celtics' offense the last few seasons, as far too many assume that the renown of a team's headliners dictate its capacity to score effectively. But Boston hasn't scrapped together even a league-average offense since 2010, and over the past two seasons in particular it has plummeted toward the bottom of the NBA rankings in offensive efficiency. That limitation has come to define these most recent Celtics teams as much as their world-beating defense. With such a thorough and consistent offensive weakness, Boston leaves its defense precious little margin for error on a night-to-night basis.
But the Celtics' D was good enough on Saturday to steal Game 1 from New York at Madison Square Garden, and for a half its offense followed suit. Jeff Green erupted for 20 first-half points on a series of strong drives and tough jumpers, and the Celtics put up 53 points on just 38 shots (good for 52.6 percent shooting). That's a strong playoff output in the general sense, but a miraculous achievement for a team so limited offensively that it ranked 20th in points scored per possession during the season. The Celtics managed to slip through the grips of the Knicks' defensive coverage for 24 solid minutes, eluding traps with smart passes and conjuring mismatches to exploit through New York's propensity to switch pick-and-rolls.
But a sobering second half swung the Celtics' offense back to its inefficient norm, in no small part because Mike Woodson's Knicks made a series of very necessary adjustments. Woodson, frankly, has come up short in this regard in recent years, but he quickly directed his team to play to Boston's limitations after an uncomfortable first-half showing.
The easiest change to make was a mere scouting-report refresher. New York's various perimeter defenders had allowed Green to drive to his right with perplexing frequency in the first half. When given that avenue, Green can be an effective off-the-dribble scorer -- big enough to create problems for the undersized wings often tasked with guarding him, and quick enough to push past tweener forwards like Carmelo Anthony and Chris Copeland. All of this would be understandable if Green were even the slightest bit ambidextrous, but his left hand seems to be present solely for symmetry -- a garnish with little practical value. Once the Knicks began to play him as such, Green turned back into a pumpkin, contributing just six points on 1-of-5 shooting from the field in the second half. Their adjusted coverage looked largely like this:
Like so many in the Celtics' rotation, Green is an imperfect player. He requires the slightest deliberate attention to nip his offensive strengths, leaving both him and Boston to subsist on his wild-card jumper and complementary skills.
With Boston's first-half leading scorer under wraps, New York turned its focus toward defending the post -- an area that had proved to be a consistent problem in the first 24 minutes. Boston wasn't manufacturing points explicitly out of post-up shot attempts, but rather using the low block as the focal point of its offensive action. It was an area of the floor from which Pierce, Garnett and Green could gain an advantage with relative certainty, helping Boston create without a reliable point guard:
The action on all of those plays is fairly consistent, as a low-block touch for any of Boston's post options would result in a double team to force the ball out of their hands. That's a reliable strategy against dangerous post threats, but only if the defense on the whole is prepared to adjust to the imbalance. On several occasions multiple defenders edged over to help against Pierce on the right block without any plan in place on how to recover once Pierce passed the ball back out, resulting in wide-open cuts for Avery Bradley and some good looks for the Celtics' perimeter shooters.
Every time Boston's offense got bogged down, the Celtics simply had to do one of two things:
1. Set up one of their bigs (or Pierce) for an impromptu post-up, guaranteeing a double team that would open up a scoring opportunity elsewhere.
2. Run an exceedingly basic pick-and-roll at the top of the key, solely for the purpose of lining up Pierce to isolate against a lesser defender than Iman Shumpert:
New York was able to get stops on some of Pierce's switching sequences, but overall the Knicks' coverage was painfully predictable. Because of that, Boston's ball handlers knew exactly what actions would cue which responses -- a knowledge that put the Celtics in control of the board, free to manipulate matchups as they wished. Pierce exploited those conjured advantages repeatedly, as Boston was allowed to get the ball to its primary scorer against a smaller opponent without even the slightest defensive deterrence. It was an exercise in repetition, and on first-half possession after first-half possession the Knicks were bludgeoned with their own reluctance to change things up.
When faced with such a sequence, many coaches would change up their gameplan completely, forcing their players to adapt to a challenge by altering direction. Yet Woodson stuck to more or less the same plan -- doubling the post and switching difficult screens -- by tightening the screws on his team's execution. Those efforts largely started by preempting the Celtics' now-predictable play preferences before they happened. In familiar sequences that are designed to set up a Boston player on the block, the Knicks now aggressively played for post position while denying entry passes. That adjustment forced Doc Rivers to move Bradley -- who was just horrible with his entry feeds on Saturday -- off the ball more often, offering an offensive player whom the Knicks could cheat off of without much penalty. Watch here how re-routing post feeds through other players mucks up the Celtics' spacing, if only because there's no optimal place for Bradley -- an inconsistent shooter -- to be:
In many cases, New York also defended the post effectively by refusing to allow Pierce or Green to establish position down low in the first place. With the Celtics entry passers slightly more tentative (given the turnovers and spacing concerns), and the Knicks nudging the posting player closer toward the wing, many would-be post possessions wound up as low-yield isolations instead:
As for those pesky switch-induced mismatches, the Knicks simply shifted the switch doctrine to a last-resort ploy. Boston's primary mode of establishing a mismatch was for Pierce to run a high screen for Bradley, which is a ridiculous sequence on which to switch. Bradley isn't the kind of player that needs to be controlled off the dribble, as he has neither the pull-up jumper nor the dribble-drive creativity to be a threat to turn the corner. And Pierce, for all of his strengths, isn't much of a threat to roll to the rim, allowing both defenders the time necessary to recover to their respective marks.
All of those tweaks worked rather significantly in New York's favor, as Boston was forced to ad-lib far too many possessions in the second half. Without many reliable ball-handlers, that's one area in which the Celtics -- sans Rajon Rondo -- really struggle; Pierce or Green can pull some attempt out of thin air, but the end result of a busted play is far too often a contested mid-range jumper or desperate flail into traffic. There's never much order to be drawn out of the chaos, and the Knicks did well to deny initial play options to force the Celtics into those crowded and uncomfortable contingencies.
Awful late-game turnovers were ultimately Boston's undoing, but the Celtics fumbled so regularly down the stretch largely because there was nowhere else to go. The post had too regularly been denied them in the second half to be a legitimate choice. Those switches at the top of the key had been too often solved and too often stalled the course of Boston's offensive possessions. All that was left was forcing passes from side to side along the perimeter, with New York's eager defenders ready to jump the passing lanes against an opponent short on alternatives.
All of this leaves Celtics head coach Doc Rivers, a solid tactician in his own right, with the next move. He’ll surely find ways to utilize Bradley more effectively -- both with and without the ball -- than the Celtics did in the second half of Game 1, and he can hope to hinge on improved spot-up shooting (Boston converted just 0.57 points per play on spot-up attempts in Game 1, roughly half of its 1.02 ppp season average) as a means of punishing the Knicks double teams. All of that said, there’s only so much he can really do with a team so light on shot-creation; Boston’s offensive limitations are real and deep-seated.
Even Garnett -- who scored a mere eight points on 4-of-12 shooting from the field in Game 1 -- may not have much room for expanded utility. He was of clear value to Boston offensively in terms of redirecting possessions and anchoring the occasional post-up, but the Knicks appear content to leave Garnett out on the perimeter to help against more pressing threats in the paint. Often, as Pierce, Green, or Bradley made any move toward the lane, Garnett's man (Tyson Chandler or Kenyon Martin) would take a few slight steps away from Garnett in order to crowd the middle of the floor. On some nights Garnett may capitalize on those chances by hitting long two-point jumpers reliably (he connected on 46.1 percent of his mid-range jumpers during the regular season), but even that outcome is one that the Knicks' defense can easily withstand. If Boston's offense is reliant on players like Garnett (and to a similar extent, Brandon Bass) connecting on long twos against a recovering defender, New York is in a good place defensively.
Of course, all of this is contingent on the Knicks' ability to maintain the same balance they managed in Game 1, which isn't necessarily guaranteed. Many of the maneuvers described above walk a fine line -- between helping and over-helping, switching as needed and over-switching -- and it's not at all inconceivable that New York's defenders could be thrown out of their Game 1 rhythm once Boston shakes things up a bit.