The Celtics picked a bad time to play one of their worst games of the season. After winning Games 3 and 4 in Boston, there was a sense of optimism that the Celtics could come up with a win in Game 5 in Atlanta.

Instead, the Celtics were just awful as the Hawks took control of the series with a 110-83 win.

It started out great for the Green. They jumped out to a 29-19 lead as Atlanta could not buy a hoop. But that lead turned out to be fools gold. The Celtics offense was horrible. It consisted of one pass and an ill-advised three pointer. The C’s shot 4 for 19 from three-point range in the first half. They settled for the quick shot instead of moving the ball and working toward a good shot. The Celtics were ranked No. 24 in the league in field goal percentage during the year and they have been the worst shooting team in the playoffs. This has been their Achilles heel and it proved to be their undoing.

Isaiah Thomas was a scoring machine in Boston as he came into game five leading all playoff scorers with 28 points per game. But Isaiah came up with a goose egg in the first half. That’s right, he did not score a point as the Celtics trailed by eight at the half.

The third quarter was just a free fall. The Celtics could not hit a shot and seemed to give up as nothing went right for them. It was like the Harlem Globetrotters against the Washington Generals, as the Hawks outscored the Celtics 61-29 after trailing 29-19. That’s downright embarrassing.

And to add insult to injury, Thomas limped off the court in the fourth quarter with an ankle injury.

Game 6 on Thursday night at the Garden becomes a gut-check game for Brad Stevens and his young team. They have less than 48 hours to get the bad taste of this loss out of their mouths and come out firing. They have to play much smarter and much harder than they did in Game 5.

The offense can’t settle for the quick three. Golden State can play that way because they have great shooters. The Celtics cannot because they do not have anyone who shoots the ball consistently well.

They cannot let Jeff Teague control the pace of play and allow Jeff Bazemore and Kyle Korver to get hot. Without Avery Bradley, the Celtics perimeter defense suffers and that was apparent in Game 5.

And most of all, they need to play with passion and intensity. That was missing from them Tuesday night in Atlanta, as more often than not the Celtics became frustrated easily and that led to poor decisions and even poorer effort.

If they can’t get their heads back into the game, the next date Celtics fans will have to look forward to is May 19, a.k.a. the NBA draft lottery.