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Penetration defense costs Celtics in overtime loss to Rockets

So far this season, Boston has been good, not great, defending isolation plays.

Houston Rockets v Boston Celtics Photo by Maddie Meyer/Getty Images

The Boston Celtics were unable to close out the Houston Rockets in a thrilling primetime home game last weekend. Though there were periods of brilliance, the Celtics suffered during their defensive lapses; they were imposing when guarding the perimeter, timid when the Rockets penetrated. Boston’s deficiencies played right into the Houston game plan.

Since the Rockets traded Clint Capela and went incredibly small, they have utilized five-out offensive scheme (meaning no player sets up inside the three-point arc). Using the swaths of space, they deliver heavy doses of isolation ball. The Rockets rely on Russell Westbrook or James Harden driving into the lanes, drawing in the defense via their shooter’s gravity, and then making the right read. Depending on the defensive reaction, driving playmakers either finish strong at the rim, draw fouls, or kick out passes to the perimeter for wide-open spot up threes.

Boston’s work on the perimeter has helped them earn their top-five defensive rating. They are continually switching, forcing opponents into bad passes or ill-timed drives. When a team slows down their offense and attacks the lanes with purpose, Boston tends to struggle.

Over the season so far, Boston has been good, but not great when guarding isolation plays. Synergy currently has them sitting in the 12th spot league-wide. They are slightly better closing out in transition, sitting at ninth place. Both of these aspects are good when looking at them objectively. Conversely, against a team with two of the best players in the league, who earn their living in isolation and transition, the Celtics needed to step it up.

Saturday started so well for Boston; they were closing out on shooters while staying composed when a drive occurred.

Their rotations were quick and incisive, allowing the on-ball defender to stay in front of the ball handler. This level of resistance deterred the Rockets from driving frequently, forcing them to settle for contested threes on the perimeter instead. Boston’s stifling defense lead Houston to shoot 11 of their 22 attempts from deep while only converting on two of them.

In the second quarter, Boston was still holding firm against Houston drives. However, the tape suggests that Westbrook was sizing up their response time, performing his due diligence on how best to combat each Celtic rotation. Basking in the chaos that often comes with too many switches, Westbrook started to gain momentum, going 5-7 from the field in the second frame.

As Westbrook began to feast, the holes in Boston’s interior defense started to show. At times, the entire defense was collapsing in to contest his drive. When a team is playing five-out offense, they’re daring the defense to sink in around a playmaker, abandoning capable shooters space along the arc.

Early in the second half, Houston began to impose their will. They stepped up their physicality on defense and their aggressiveness on drives. With data on Boston’s defensive schemes gathered during the first half, the Rockets came out of the locker room with an adjusted gameplan: get the ball into the lane at speed. The Celtics lost their composure as they struggled to match the increased intensity, something which directly correlates in the box score with Houston winning the quarter 36 to 22.

Houston was driving and kicking to the open man every time help defense arrived, which enabled cleaner looks from deep. As a result, the Rockets shot an efficient 7-of-15 from deep for the quarter.

Houston also hit on 13-of-22 from the field overall in the third quarter.

When discussing how the Celtics rotational scheme can generate open looks, this play here is a picturesque example:

After competently dealing with Houston’s scheme for the entire first half, the Celtics couldn’t handle the Rockets in the third. So much so, that Houston won the quarter 36 to 22—the only quarter they won.

The fourth quarter offered glimpses into both aspects of the Celtics defensive performance. At times they seemed impenetrable; during others, they were inviting Houston in. Boston switch maddeningly from a fantastic stop to an unfathomable lapse in subsequent plays.

The key to this quarter was holding James Harden to 0-of-6 shooting, which is no easy feat and a testament to Boston’s prowess when locked in on defense. Westbrook caused the problems. He found lanes to the hoop with an uncomfortable regularity.

Sometimes it was by pure skill.

Other times, Boston’s self-inflicted defensive lapses returned easy Houston buckets.

Overall, the Celtics made the necessary adjustments following their third-quarter mauling. They stayed in front of the driving ball handler, only rotating when severe mismatches occurred. Reacting in this manner allowed the Celtics to keep their defensive shape. In turn, Boston forced Houston to revert to their usual game plan: launch it from deep at the first sign of daylight. The home team won the fourth quarter 26-23, thanks to a moment of brilliance from Jaylen Brown.

Gassed, both teams combined for 13 points in overtime. Boston ultimately fell short at the last hurdle, a heartbreaker.

Houston is a team designed to attack the perimeter based on isolation drives into the teeth of the defense. Boston is at its worst defensively when opposing players drive the lane with purpose; this matchup was intriguing from the beginning.

You either win, or you learn. The lessons Boston can and will take from this game could prove invaluable when the playoff’s roll around. If the Celtics can fix the weaknesses that were exposed in this game, they may come to look back at this loss as a win.