Maybe Jaylen Brown best summed up the end of Boston’s 10-game winning streak when asked about how Marcus Smart’s last-second floater improbably bounced out during a one-point loss in Sacramento on Sunday.

“The ball was just sitting on the rim and we didn’t deserve it, so it didn’t go in,” said Brown.

It was brutal honesty. The Celtics spent much of their winning streak flirting with disaster — whether that was a pair of double-digit comebacks early against the Knicks and Bucks, or Friday’s rally from 15 down to edge the basement-dwelling Warriors. Finally, the Basketball Gods punished Boston for its haphazard ways.

It’s hard to be upset about a 3-1 week, and yet there has been some obvious slippage in Boston’s play even as its winning streak hit 10 games. An unforgiving schedule awaits now and the Celtics need to ratchet up their focus. Let’s hand out Week 4 grades.

Daniel Theis (A-)

Theis’ undefeated record as a starter — 13-0 entering Sunday’s game — might still be intact if Smart simply held onto the offensive rebound he collected with 14.7 seconds to go (what’s more, Theis would have accounted for the winning bucket). Alas, he’ll have to settle for being one of Boston’s bright spots this week, owning a net rating of plus-20.7 in three appearances, the best number among Celtics regulars.

Theis missed a game with a dislocated finger but quietly averaged 10.7 points and 7.3 rebounds over 22.1 minutes per game.

Marcus Smart (B)

Sure, he turned in his worst shooting night of the season against the Kings (2-16 FG, 1-8 3PT, 5 points) and that floater improbably bounced off the front rim at the buzzer. What’s more, Smart couldn’t hose down Buddy Hield as he went off for 35 points. Still, Smart spent his week hounding the likes of Luka Doncic, Bradley Beal, and Hield, and he still had one of the best net ratings (plus-12.1) on the team.

In fact, Boston’s defensive rating spiked 7.5 points when Smart wasn’t on the court over the past four games. Despite his dud in Sacramento, Smart shot 43.8 percent beyond the arc (on eight 3-point attempts per game) and averaged 13.5 points and 6 assists.

Jaylen Brown (B-)

Another strong statistical week for Brown, who averaged 21.8 points while shooting 50 percent from the floor and 52.9 percent beyond the arc. He added a team-bests while averaging 8 rebounds and 1.5 steals.

So why the harsher grade? His turnovers spiked to 2.3 per game — a concerning team-wide trend — and the Celtics were outscored during his 143 minutes of floor time.

Jayson Tatum (C+)

Let’s start with the negative here, too: Tatum shot just 32.4 percent overall this week and 21.1 percent beyond the 3-point arc. He made a ghastly 31 percent on shots at the rim (9 of 29). And yet Tatum was still somehow plus-48 in 138 minutes of floor time.

If Tatum doesn’t swipe the late-game jump ball in Golden State, Boston’s winning streak might have ended at nine. If Tatum’s layups ever start falling, the Celtics won’t need last-second heroics to win games.

First-Half Kemba (D+)

It’s hard to get too worked up about Walker’s first-half shooting woes when he’s typically been a second-half monster, but the splits are harsh. Walker shot 32.1 percent overall (9 of 28) in the first half of the past four games and 23.5 percent beyond the 3-point arc (4 of 17). He was minus-17 in his 64 first-half minutes.

This is a season-long trend, too, with Walker shooting 30.9 percent overall and 24.5 percent beyond the 3-point arc in the first half of all 12 games. The Celtics need better starts in general and Walker needs to set that tone.

Robert Williams (D)

We’ll chalk some of his struggles to minor maladies like the hip and ankle injuries he’s been dealing with. But, after his big night in San Antonio, Williams had a forgettable week. He was minus-14 in 17 minutes against Dallas and minus-13 in seven minutes at Sacramento.

He looked tentative in both games to start the trip, as if he didn’t trust his ankle when running to the rim. He had no blocks in either of those games. We’ve gotten on Williams about his injury blips and lack of availability but it’s so very clear that he needs to be 100 percent to be the impactful player that he can be, and he just doesn’t look it at the moment.

Grant Williams (D-)

Tough go for the rookie, whose week ended with a DNP in Sacramento as coach Brad Stevens hunts for his most reliable bench options. The typically steady Williams had five turnovers in 34 minutes of play this week and his shooting hasn’t helped his case as he’s missed all 14 of his 3-point attempts this season (and he’s 9 for 32 overall).

When his plus/minus dips into the negative, you know Williams isn’t himself. He needs to fight through the rough patch and get back to being someone who positively impacts winning. 

Javonte Green (D-)

Maybe it’s just the fact that he was at the head of the class last week but Green did little to sustain his momentum, especially as the Celtics looked for bodies to fill Gordon Hayward’s void. Green was minus-27 in 26 minutes of floor time.

He got his first NBA 3 to drop in a decent night against Dallas but played only 12 minutes the rest of the week while logging a DNP at Golden State. Green lost Buddy Hield early against Sacramento and only played six minutes total. Rookies are going to have these sort of blips and it’s on Green to fight through it.

The Celtics had a decent offensive week, putting up an offensive rating of 115.3, a mark that’s 3.3 points above their No. 2 ranked season average. And yet there was one glaring area of concern: Turnovers. Boston sits atop the NBA in turnover rate, giving away the ball on a mere 11.8 percent of possessions. That the nearest team is 1.4 percent behind them shows just how well Boston has taken care of the ball this year — at least until recently.

And it’s not just that the Celtics gave the ball up more, it’s what happened after. Boston had a season-high 15 turnovers against the Kings and that led to a whopping 19 points for Sacramento. For comparison, the Kings turned the ball over 12 times but Boson generated only eight points. Against Golden State, Boston had 14 turnovers leading to 19 points. Versus Washington, the Celtics coughed it up only nine times but Washington generated 16 points off of those turnovers. Live ball turnovers and poor transition defense in those instances has really hurt Boston when you consider how stout the C's defense has been when they allow themselves to get set.

Grade: C

The Celtics turned in two of their least-inspiring efforts this week. Boston offered little resistance as Beal and the Wizards put up 133 points, the Celtics content to just trade baskets against a team with the league’s 29th ranked defense. Against Sacramento, the Celtics let Hield and the Kings’ 3-point shooters get comfortable early and Sacramento shot 40 percent beyond the 3-point arc (Boston has limited opponents to 33.3 percent shooting for the season, the seventh best mark in the NBA).

Boston still ranks 10th in the NBA while allowing 103.9 points per 100 possessions this season, but that number spiked to 109.8 in the four games this week. Yes, they played two of the league’s best offenses (Washington, Dallas) but the defense just wasn’t good enough overall.

Grade: D

It’s on Stevens to get more consistency out of his groups, whether that’s getting the starters to click earlier or finding the right reserve groups to sustain a high level of play. Injuries have complicated that process but it’s clear Stevens spent the latter part of the week searching a bit. Stevens will have to press the right buttons this week as the competition level jumps up to close out this west coast trip.

Grade: C+

It was a fairly healthy week for the Celtics beyond missing Gordon Hayward. Robert Williams and Theis each missed a game due to injury. Grant Williams and Javonte Green each logged one healthy DNP while fellow rookie Vincent Poirier played only nine minutes in one appearance.

The Celtics are a little dinged up heading to Phoenix, though, with Smart noting he has a bruised hip and a couple sprained fingers, while Walker also banged his knee against the Kings.

Call it an overreaction and maybe grades would be a bit cheerier if Smart’s layup drops for another undefeated week, but it wasn’t a particularly inspiring seven days for the Celtics. There was obvious slippage before the winning streak ended and the end of this trip could be a real wakeup call if the Celtics don’t play with a greater sense of urgency on both ends of the court.

Grading against what this team has already shown itself capable of delivers a sobering mark this week. There is undeniably a lot of room for improvement.

Grade: D+