Celtics’ loss to Rockets latest reminder Boston’s late-game execution is cause for concern

LOS ANGELES—It should be easy to ignore the Celtics’ defensive blunders down the stretch against Houston on Monday. Bad games and bad moments happen to every team a few times a season. Boston was showering in champagne last June, so it’s tempting to write this game and their recent “slump” off as a simple mid-season malaise.

Except poor late-game execution is not just a one-game thing for Boston. Or two games.

Monday night was the ninth time this season the Celtics had a fourth-quarter lead — this time it was a dozen points against the Rockets — and found a way to lose. That equals the number of blown fourth quarter leads Boston had all of last season, and we’re just over halfway through this season. Monday was the seventh time this season Boston has blown a double-digit lead. And none of that counts games Boston hung on to win despite late-game struggles.

“We got clean some things up, but just our will to win, we will to figure it out,” All-Star Jayson Tatum said last week after his team almost blew a late lead against the Clippers and had to win in overtime. “I’d rather learn from a win and learn from a loss, for sure.”

Boston didn’t learn much from that win, based on what we saw Monday. The Celtics had two ugly defensive lapses in the final seconds against the Rockets. The first was Luke Kornet losing Alperen Sengun for a dunk to give Houston the lead.

Tatum tied the game up again with a driving layup, but on the final play of the night Kornet and Jaylen Brown decided to pre-switch but did so after Fred VanVleet was handed the ball, which left Amen Thompson wide open and guarded now by an out-of-position Brown. Thompson has quickly become too good to give him that, he hit the game-winner.

It’s not just this one game, or just games the Celtics lose, where their end-of-game execution is a concern. Last week against the Clippers Boston led by six with 1:03 remaining in regulation. In that final minute, the Celtics had two turnovers due to a trapping defense, and one missed shot while the Clippers — playing without James Harden, Norm Powell, Kawhi Leonard or Ivica Zubac — made enough plays to force overtime. Boston hung on to win in OT, but after the game did not sound like a team that has won a ring.

“I take accountability…” Brown said. “We had some turnovers late in the fourth quarter. It was, I guess, some different coverages the Clippers throwing that at us, but they did a good job at trapping us in the corners and stuff. They made the game closer then it probably should have been, but we just gotta be better.”

Joe Mazzulla took the blame for the loss on Monday to Houston — he said he told Brown and Kornet to switch too late — but admitted after the Clippers game that preparing for late-game moments is tough for a coach to practice.

“At this time, we’re not going to be able to simulate the physicality of what it’s going to take, but you can work on it and just continue to stress it, and there are some things where we can get better,” Mazzulla said in Los Angeles.

Like much of Boston’s season, things are painted with a darker brush than they would be if this were not a team that waltzed to the NBA title a season ago. The Celtics are still 13-9 with a +4.7 net rating in clutch games (within five points in the final five minutes). Tighten that up to a game within three points in the final three minutes and the Celtics are 11-8 with a -1.4 net rating. Celtics backers can also point out that an elite defender in Derrick White did not play against Houston, and Boston has dealt with injuries this season, just like every other team.

However, Boston has set its bar much higher — and Mazzulla wants it that way. This is a team looking to hang banner No. 18. That’s why their defense being a little worse (but still fifth in the NBA), or Brown’s shooting becoming a little less efficient — his 54.3 true shooting percentage is below league average — draws attention.

It’s the end-of-game stuff that is most concerning because if Boston is going to beat teams like Cleveland, New York and Milwaukee in the East playoffs — let alone Oklahoma City, or even Houston, in a possible Finals matchup — it’s going to happen in close games. The Celtics can’t keep having these lapses and expect to return to the top of the mountain.

Brown said it best, “We just gotta be better.”