By Matthew Geagan, CBS Boston

BOSTON (CBS) — The Celtics wrapped up their west coast trip with a loss to the Utah Jazz, another defeat that could have gone in their favor had they exerted a little more on the defensive end. It’s a troubling trend that has plagued the Celtics all season, and now they sit at a frustratingly average 12-11 on the year.

READ MORE: Somerville Woman Accused Of Drunk Driving After Crashing Into Pole In NH

Boston got an up-close look at how the best team in basketball operates on Tuesday night. After a hard-fought first half, Boston folded in the third and fourth quarters. The Jazz were held to  just 48 points in the first half, but the Boston defense disappeared in the third quarter and surrendered 42 points in the frame. The Celtics were still able to pull within four points of Utah on a number of occasions in the fourth, but ultimately squandered any opportunity to stun the Jazz by leaving shooters open or allowing clear paths to the basket.

Donovan Mitchell was met with very little resistance in the second half, scoring 24 of his 36 points after the break. The Jazz were without starting point guard Mike Conley, but his replacement, Joe Ingles, was allowed to go off for a career-high 24 points off 5-for-12 shooting. All of his makes were from downtown, and he added nine points at the free throw line off 10 attempts. For the season, Ingles is averaging 1.2 free throws per game.

Any time the Celtics got close, the Jazz made a splash from deep or took advantage of no Boston bodies in the paint. The Jazz displayed some incredible ball movement to find open shooters, and the Celtics had no answer.

“The fourth quarter is when we’re supposed to be at our best defensively, and it was our worst,” Jaylen Brown said after the defeat.

READ MORE: Three Men Charged In Cheating Scheme At Encore Boston Harbor

Brown returned after missing the last two games with knee soreness and led the charge for Boston with 33 points. But he was not happy with the team’s effort in the final frame, and did not hold back when discussing the loss.

“We [expletive] should take it personally,” said Brown. “The fourth quarter was embarrassing. That’s the time when we’re supposed to be our grittiest and it seems like we fell apart in a sense. That’s a lack of toughness, that’s a lack of leadership and a lot of that is on me. As a leader of the team I take responsibility for how we respond and how we came out in the fourth quarter. It just wasn’t there for us.

“The way they played with the freedom, the flow they have to their team is really good right now,” Brown said of the Jazz. “We’ve got to find a better flow for ourselves because we have some disconnectedness at times. The game almost seems like it’s a little bit harder than it should be. If we just trust each other and are in the right spots, the game will be a lot easier than what it has been for us.”

The loss concluded a 2-3 road trip, an expedition that should have gone a lot better for Boston. The Celtics blew an extremely winnable game against the Kings, and after their best win of the season over the L.A. Clippers last Friday, they closed it out by dropping two more winnable games. The opportunities were there in Utah, but open looks and off-ball fouls led to their demise. All of that is the product of a lack of focus.

MORE NEWS: Stores Are Closing But This Discount Chain Plans To Move In

The Celtics have a lot of issues at the moment, from the team’s lack of urgency on defense to Kemba Walker’s abysmal shooting on a nightly basis. A healthy roster would help, but a lot of their issues are fixable with a little more effort. The Celtics have had a handful of wake-up calls this season, and hopefully this road trip serves as their loudest. Boston can’t simply hit the snooze button and expect to be better anymore.