What's going on with the Boston Celtics?

That's become a familiar refrain this season, as the Celtics have come nowhere near living up to the lofty expectations set for them heading into the season. And their performance Tuesday night did little to answer that question. They were run out of the gym by the Toronto Raptors on national TV, losing 118-95 in a game they trailed by 31 at one point. 

It started out well, as the Celtics led 32-30 after the first quarter, but the Raptors went on an 18-0 run early in the second frame to take control, and the Celtics never recovered. Things got so bad at one point that the usually mild-mannered Brad Stevens was caught using a powerful expletive toward of the referees on the broadcast. 

The Raptors deserve plenty of credit for Tuesday night's outcome. They shot the lights out of the ball, going 17-of-36 from 3, limited their turnovers to just eight and played outstanding defense. Perhaps most impressively, they held Kyrie Irving to just seven points, his first game scoring in single digits since October. 

Games like this are going to happen throughout the course of an 82-game season, where one team is playing at their peak, and the other is truly off-color. But even though it may be unwise to read too much into one single loss, this performance by the Celtics was yet another troubling sign. 

Coming out of the All-Star break, they lost a tough one to the Eastern Conference-leading Milwaukee Bucks on the road, which was not a bad loss by any means. A few nights later though, they were embarrassed by the lowly Chicago Bulls, who won for just the 16th time this season. 

That suddenly put a lot more emphasis on Tuesday night's contest, which was a chance for the Celtics to redeem themselves and get back on track against one of the East's best teams, and a potential playoff opponent -- which is why it was so troubling that they flat-out folded after giving up that big run to the Raptors in the second quarter. It's one thing to simply get outplayed by another great team; it's another to get outworked in the process. 

Additionally, yet another regular season loss drops the Celtics to 37-24, putting them two games behind the Philadelphia 76ers for fourth in the East, and three games behind the Indiana Pacers for third. It's becoming increasingly likely that the Celtics won't have home-court advantage for the first round of the playoffs, something that would have been unthinkable just a few months ago. It's also not encouraging for their prospects after they went 1-7 on the road last postseason, and are just 14-16 away from home this campaign. 

Following their loss to the Bulls over the weekend, a defiant Irving told reporters, "I don't get frustrated about this stuff anymore. It's just part of the regular season. In the playoffs, when you can plan for a team, prepare for a team, I still don't see anybody beating us in seven games."

There are still some reasons to buy in to Irving's confidence that the Celtics can succeed in the playoffs -- namely Irving himself -- depending on their matchups, but Tuesday night's dispiriting performance certainly wasn't one of them. In a season full of them, this was yet another low point for the Celtics.