BOSTON -- After Celtics head coach Brad Stevens watched Utah Jazz power forward Derrick Favors slam home three thunderous alley-oop dunks early in the fourth quarter here at TD Garden on Saturday night, he decided he had seen enough.

Out came Al Horford, Gordon Hayward and Jaylen Brown, joining Jayson Tatum on Boston's bench.

In came Brad Wanamaker, Guerschon Yabusele and Daniel Theis -- the three players who typically sit at the end of the bench and watch.

They, alongside Semi Ojeleye and Kyrie Irving, attempted to breathe some life into the Celtics, though it was an ultimately futile effort, as Utah went on to claim a 98-86 victory over Boston.

But while Stevens sent a message to his team on the court, Irving sent one to his young teammates -- and specifically Tatum and Brown -- in the locker room afterward.

"I think guys have gotten better," Irving said. "I think that guys want to take advantage of their talent.

"I think last year, the young guys that are in the locker room now, some of the guys that are playing, they were a little bit younger. They weren't expected to do as much, and I think that the amount of pressure that we put on them to perform every single night is something that they have to get used to, being part of a great team like this."

"If you're not playing to the standard then, as a team, we just don't all click," Irving continued. "I think once we get that, and we find that consistency, we'll be good."

Brad Stevens has to fix what is the 27th-ranked offense in the NBA through Boston's first 16 games of the season. Bob DeChiara/USA TODAY

A year ago, the Celtics were supposed to be built around Irving, Hayward and Horford. But then Hayward suffered a gruesome season-ending injury six minutes into Boston's season opener, and both Tatum and Brown were thrust into far larger roles than either ever were expected to be in.

Tatum and Brown thrived far beyond what could be reasonably have been expected from them -- success that appeared to have Boston as well-positioned as any team in the league for the future. It also was a major reason why the Celtics entered this season as favorites to emerge from the Eastern Conference and reach the NBA Finals for the first time since 2010.

But then the season started, and Tatum and Brown haven't delivered in nearly the way the Celtics would've hoped.

Down on their luck Former third-overall draft picks Jaylen Brown and Jayson Tatum were exciting producers for the Celtics last season, but both are off to slow starts this season offensively. Averages 2017-18 Brown 2018-19 Brown 2017-18 Tatum 2018-19 Tatum Minutes 30.7 29.1 30.5 32.3 Points 14.5 10.9 13.9 15.9 Assists 1.6 1.3 1.6 2.1 FT Attempts 3.3 2.1 3.2 3.4 FG/FT/3% 46.5/64.4/39.5 36.2/64.5/27.3 47.5/82.6/43.4 42.4/88.9/39.4 >> Celtics average 19.4 FT attempts per game (29th in NBA)

"Whatever word you want to use," Irving said, when asked if he thought his two young teammates were pressing too much. "I just think that, for the amount of work that, like I said before, that guys put in, I think they have expectations for themselves, and I think that's completely normal. Getting beaten down on [missing] shots or not being in the right spots ... I think that we just have to find the happy balance between those two.

"Going on this early part of the regular season, teams are coming at us, so they're expecting to make shots, they have a great rhythm; then we get hit in the mouth a few times, and we just gotta be able to respond."

The Celtics have, far too often, struggled to respond this season. Boston is now 9-7 after Saturday's loss and has dropped five of its past eight games. And had there been a couple of different bounces both Friday night against the Toronto Raptors and last week in Phoenix against the Suns, that is a stretch that easily could have been seven losses out of eight.

Stevens, typically one of the league's most reserved coaches, not only made a statement on the court by playing those reserves alongside Irving during a stretch of the fourth quarter when -- while unlikely -- Boston still had a chance to reverse a double-digit deficit, but he then doubled down on his decision by stating postgame that his team simply isn't tough enough.

"We have to build a tougher mindset than we have," Stevens said. "I mean, we just don't have that mindset yet that we need."

Horford offered his take.

"It's very clear that we're concerned about shots, and our offense," he said.

Stevens admitted that some of that could be attributed to players hanging their heads after missing shots. That certainly could be true for Brown, who didn't speak to reporters after Saturday's game. Brown is now shooting 36.2 percent overall and 27.3 percent from 3-point range after going 1-for-9 on Saturday, including 1-for-6 from the 3 line.

Since making his first two shots in Friday's win against the Raptors, Brown -- who was benched at the end of regulation and in overtime during that game -- has gone 2-for-18 overall and 1-for-10 from 3.

"You know, I had an old friend [Paul Patterson, a longtime coach at Taylor University, an NAIA school], and the phrase that his team used was, 'The game honors toughness.' And boy, is that true," Stevens said. "You see that over and over.

"And so, I would say that if we're struggling with the ball going in the hole that we should just lock into what we need to do better, and that will take care of itself."

Tatum, meanwhile, had 10 points on 5-of-11 shooting in 24 minutes Saturday night -- a step back from his 21-point performance in Friday's overtime victory. Irving specifically referenced Tatum's decision to settle for a long 3-pointer rather than attacking a mismatch against Favors, a far bigger player, on Boston's opening possession.

"I just think the start of the game for us was a telltale sign of just how the night was going to go," Irving said. "We get a switch with [Tatum] out on Derrick Favors and kind of expected him to attack [and he didn't]. That's our first possession of the game."

It was only 24 hours earlier that the Celtics played one of the most entertaining games of the season on this same floor, going toe-to-toe with the Raptors and winning a thrilling contest. Then, Saturday night, the Celtics came out and laid an absolute egg, rather than building on that success.

"I would say, thus far, that's us," Stevens said after the game. "I mean, that's who we've been."

Even with the expectations placed upon them, the Celtics entered the season knowing there would be some growing pains at the start.

Hayward was coming back from missing all of last season, and while he continues to show signs of progress, there have been moments -- including when Hayward attempted to dunk on the break and was blocked by Donovan Mitchell, exposing his lack of explosion at this point in his recovery -- that show he still has a long, long way to go. And several players were going to have to adjust to new roles with both Hayward and Irving -- who missed the playoffs due to knee surgery -- returning to action.

But those growing pains were supposed to be helped along by the play of Tatum and Brown and the additional steps in their development they were expected to take this season.

So far, though, things haven't worked out that way.