After Marcus Smart says the Celtics aren't together, Kyrie Irving responds by saying "that's Marcus' opinion." (1:11)

TORONTO -- After the Celtics suffered their worst loss of the season, a 118-95 drubbing Tuesday at the hands of the conference rival Raptors, Boston starting shooting guard Marcus Smart said the team is "just not together," in contrast to the Celtics squads in recent seasons that exceeded expectations.

"What are the main ingredients to those collapses? Not being together," Smart said. "And that's it. We're just not together. Plain and simple. That's it. Because if we were together, that wouldn't happen. We're all talking and linking up, but like I said, it's something we're going through, and it's something we're going to have to continue to work at and figure it out."

The Celtics and Raptors played a crisp, competitive first quarter befitting two Eastern Conference preseason favorites. They combined for 15 assists and only three turnovers, with the Celtics leading 32-30 headed into the second quarter.

But following a pair of made free throws by Celtics backup point guard Terry Rozier, the Raptors mounted an 18-0 run to lead 48-34. The Celtics never narrowed the deficit to fewer than 11 points, as the Raptors dominated the game with precision passing, quick second-side actions and transition baskets.

"I thought we were just outplayed in every which way," Celtics coach Brad Stevens said. "I don't want to take away from Toronto, but am I thrilled about how we played? No."

After the game, Stevens said the Celtics' defensive failures were the latest in an unsettling pattern during their current three-game losing streak.

"This is real," the coach said. "The reality is that we're taking a lot of shortcuts and not being as solid as we have been in the past in the last two games. I thought we were really good against Milwaukee. So, it's not like we don't know what we need to do, but for whatever reason, we've taken too many shortcuts. You can't do that against any team. Certainly tonight, they exposed us and played great."

Asked how the Celtics could address the defensive shortcuts characterized by Stevens, Celtics guard Kyrie Irving responded, "I don't know. It's up to Brad."

In recent weeks, Irving has been expressive about his perceptions of the challenges present in the Celtics' locker room this season and the specific burdens of assuming the mantle of leadership of a talented roster. He has openly challenged teammates, both on the floor and in explicit comments to the media.

On Tuesday, Irving was asked whether he agreed with Smart's blunt assessment of the Celtics as a team that isn't together.

"That's Marcus' opinion," Irving said. "I respect it."

Stevens was more decisive in his appraisal.

"We have to be more connected as a team," he said. "It's been a theme for a while."

In addition to Tuesday night's blowout, the Celtics were embarrassed Saturday by a 16-44 Chicago Bulls team, and Boston hasn't won since the All-Star break.

Smart and Celtics big man Al Horford expressed concern that this season's Celtics were less resilient in absorbing blows from opponents. Last season, Gordon Hayward was lost on opening night, and Irving was sidelined in early March for the remainder of the season. The undermanned Celtics took the Cleveland Cavaliers to seven games in the Eastern Conference finals.

"For whatever reason, we're not fighting, continuing to fight at that level like in the past," Horford said. "It happened in Chicago where we didn't recover, and it happened again tonight."

Smart, who is noted for his defense and ability to impact the game on the margins, expressed frustration at his team's inability to capitalize on the sort of effort plays that had been its hallmark.

"Right now, it doesn't surprise me because that's just how things are going for us," Smart said. "It surprises me in the fact that that's not who we are, but at this moment, it doesn't. We've just gotta fix it. Like I said, it's going to be fixed. It can and will be fixed. It's just not going at the pace we expected it to."

Patience is at a premium for Boston. Tuesday's defeat dropped the Celtics to 37-24, fifth in the Eastern Conference and two games behind the Philadelphia 76ers. The Celtics are 7½ games behind Toronto for the No. 2 slot, their seeding in last season's playoffs.

The Celtics will have an opportunity to erase Tuesday's blowout at Toronto with a home date against the 37-23 Portland Trail Blazers on Wednesday at TD Garden (8 p.m. ET, ESPN).

"That's the thing about this game," Smart said. "You've got to have a short memory. This game's over with, and we've gotta focus on tomorrow and get ready to come out and play."

Smart said that despite the slower timetable, he had reason to believe the Celtics could mold themselves into a cohesive unit in time for the postseason.

"Because everybody here's professional," he said. "Everybody here plays basketball, and everybody is really talented on this team. And I know the potential that we all have. So, it's just a matter of time."