By Matthew Geagan, CBS Boston

BOSTON (CBS) — Brad Stevens has often been lauded for being a mastermind at drawing up successful after-timeout plays. But on Monday night, the Celtics head coach drew up a play that may go down as the worst to ever be scribbled on a whiteboard.

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The “play” occurred during one of the most frustrating stretches of Monday night’s 115-104 loss to the Denver Nuggets. The Celtics had the ball with 32.8 seconds left in the third quarter, up 80-75, but they had no desire to go for a two-for-one. Instead, Jayson Tatum clanged a corner three with 17.5 seconds left, part of his 1-for-5 night from downtown. The Nuggets collected the rebound, set up their offense, and Torrey Craig drained a corner three to make it a two-point game with 1.1 seconds left.

But instead of just inbounding the ball and letting the third quarter mercifully come to an end, Stevens called a timeout and drew up a desperation heave. Marcus Morris propelled the inbound from under the Denver basket — directly to the Denver bench. To say the pass was wide left of Jaylen Brown would be an understatement. It was a bold strategy, to both not run an actual play and to give the Nuggets the ball back under their hoop.

Denver took advantage, as they caught Jaylen Brown napping on his perimeter duties, letting Craig sneak around him for an easy cut to the basket. Like Brown, Daniel Theis was napping underneath the hoop, and Craig had an easy dunk to tie the game at 80. It was a five-point swing that the Celtics never recovered from, as the Nuggets started the fourth quarter on an 11-2 run that essentially clinched the game for them.

The Celtics pulled within five in the closing minutes, but it was too little too late for a team that made too many mistakes on Monday. Stevens agreed that the stretch at the end of the third was a “killer sequence” for his team, and shouldered all the blame for the defeat.

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“I probably shouldn’t have called the timeout. I’m going to lose it going into the fourth, and you maybe think if you can get a matchup down the court then that’s a good thing. Otherwise, be safe. I shouldn’t have done that, and then we just didn’t respond to that,” he said. “Getting back-cut for that dunk and then the start of the fourth. We needed to respond better and we didn’t.

“We’ll be in that position again where something bad happens and the air gets taken out of your team a little bit, and you have to respond, and tonight we didn’t do that against a good team who took advantage of it,” he concluded.

Stevens said the team has successfully run the deep look before, and there were other options in place if the Nuggets had shut that off. But the execution, as it was throughout much of Monday’s loss, was non-existent on the play.

“There was a deep look, but we had safeties. Ultimately, if you can get a matchup you like on the deep look, we’ve thrown that before and had success. But obviously, it didn’t work, and that’s on me for calling the timeout,” said Stevens.

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It was a perfect example of a coach overthinking things at an extremely inopportune time. In a season that has been filled with frustrating losses, the sequence at the end of the third quarter on Monday night will stand out as one of the worst 32 seconds of the campaign.