MILWAUKEE — For the first five games of the playoffs, the Boston Celtics looked like the team they were expected to be in the regular season. Kyrie Irving showed how much he was missed during last season’s playoff run, Gordon Hayward looked as good as he ever has in a Celtics uniform and the defense was in sync. They rattled off a four-game sweep of the Indiana Pacers in the first round, then came into Milwaukee and made a statement with a 22-point win in Game 1 to steal homecourt advantage. 

But all of that good work went down the drain during one disastrous stretch in the third quarter of Game 2 on Tuesday night. After Jaylen Brown rocketed a 3-pointer from the left wing off the backboard on the other side of the rim, the Bucks went down to the other end and got Pat Connaughton a layup, which started a 22-2 run to close the third, and, for all intents and purposes, end the game. With each team pretty much mailing it in at that point, the Bucks cruised to a 123-102 win to even the series at 1-1. 

The stretch was a throwback to the Celtics’ tumultuous regular season, when they suffered similar collapses on an all-too-regular basis. Bad defense led to bad offense and all of a sudden a manageable five-point deficit turned into a 26-point hole that was far too deep to climb out of in one quarter. 

“I thought they owned their space on both ends of the court better than we did,” Celtics coach Brad Stevens said. “I thought our reaction to that was to settle on offense and it led to some run outs. Then it just steamrolled on us. They were great tonight.”

As Stevens noted, the Bucks were indeed great on Tuesday night. Needing an impressive response after getting blown out on their home floor in Game 1, the Bucks delivered. Giannis Antetokounmpo responded from one of his worst games of the season with 29 points and 10 rebounds, including 15 in the Bucks’ dominant third quarter. Khris Middleton was also tremendous, going 7-of-10 from downtown en route to a 28-point night and they set a franchise postseason record with 20 3-pointers. They trusted in the system that had gotten them to this point, and it delivered. 

But while the Bucks deserve plenty of credit, the Celtics played a role in making it much easier for them than it was in Game 1. There were the little things, like turning the ball over more and giving up more offensive rebounds, but they also had far too many breakdowns on both offense and defense in that perilous third quarter. 

“I think that they just took control of the game and really did a good job of getting out and getting some good looks in transition,” Al Horford said. “We didn’t do a good enough job there getting back and getting matched. They just took over.”

In Game 1, the Celtics’ defensive gameplan was on point. That was especially true in transition, where they were able to form a wall at the top of the key to prevent Giannis from getting straight to the rim. But they also had success because they were scoring enough to get back into a set defense and not worry about being perfect in transition. Those two aspects are interconnected, and the third-quarter collapse happened because the Celtics too often took quick, ill-advised shots, which led to more and more transition opportunities for the Bucks. 

“We weren’t very good on either end, but I do think that our offensive settling, and some of the shots that we forced steamrolled on us in a lot of ways,” Stevens said. “Hopefully we can be better at getting better shots, getting able to set our defense so we’re not scrambling all the time, and doing a better job flying around and being in their airspace.”

Now, the question for the Celtics becomes: how do they respond? Collapses like the one in the third quarter happened time and time again in the regular season, which was bad enough. But the Celtics often let those kinds of performances spiral into bigger problems. Whether it was long team meetings, snapping at each other in the press or multi-week swoons, the Celtics had trouble moving on from a bad night. It goes without saying, but there’s no time for that in the playoffs. 

They better be ready to go in Game 3, or they could lose the homecourt advantage they stole in Milwaukee just like that. But to their credit, they said and did all the right things after Game 2. There was no closed-door meeting, no sulking; the Celtics gave the Bucks props for how they played, took responsibility and vowed to be better on Friday night. 

“This is what I signed up for,” Kyrie Irving said. “This is what Boston traded for me for. Being able to go back, get back in the trenches and get ready for another battle on Friday. This is what you live for. Basketball is fun when it comes like this and you have to respond. This is the type of basketball you want to be playing.”