There are nights like this in the NBA sometimes. On nights when one team is healthy, rested and ready and when the other is not, you get scores like the 105-86 beatdown the Celtics put on the Jazz Wednesday at the TD Garden. (Recap)

The Celtics had three days to get their legs right after their stretch of eight games in 12 days, while the Jazz came in smack in the middle of a four-game East Coast stretch with Deron Williams hurting (bruised calf, back sprain) and without Kyle Korver, Ronnie Price or C.J. Miles.

The Celtics had no such worries, not with seven players scoring in double figures, assists on 30 of 41 field goals and a defensive effort that took away Utah’s vaunted movement.

Consider the two perspectives of the coaches:

“I just thought the execution tonight was absolutely fantastic,” Doc Rivers said.

“We looked like we never played a game that was difficult,” Utah coach Jerry Sloan said. “And it wasn’t a lot of fun to watch.”

That about sums it up. But there was more to it than that, of course, and here are three things we learned:

THE KEVIN GARNETT-WATCHERS NEED TO TAKE A DEEP BREATH

You can generally tell how happy Garnett is with the way he played based on his postgame quotes. If he’s deep or philosophical, he’s probably dwelling on something he didn’t like. If he’s cracking jokes, you know he had a night when he goes 7-for-10 from the field, scores 18 points and generally is a force on defense.

“It feels good to be healthy,” Garnett said. “It feels good to run. It’s like running free in a cornfield.”

So yeah, KG was happy with his performance. In his nine games this season, Garnett has had solid games most nights, a few spectacular ones (Wednesday night would have qualified if it wasn’t a blowout) and a few clunkers (Philly, New Jersey).

What we know at this point in the season is that Garnett still is working his way back into a rhythm. What we don’t know, not yet anyway, is whether he will be the KG of 2007-08 again.

Frankly, that’s to be expected. In our age of constant, and instant, analysis we sometimes forget to look at the whole picture. But when we step back, we see a few trends emerging.

First, the Celtics don’t necessarily need Garnett to be the old KG just yet. They are 8-1 and he has been the best player on the floor no more than a handful of times.

Second, Rivers has been fairly consistent in keeping Garnett’s minutes in the 30-32 range. He has hit the 35-minute mark exactly twice — against Minnesota and Phoenix in back-to-back games — and he couldn’t get anything to fall the next night in Jersey. The two things probably are not coincidental.

With three days off, Garnett was athletic and spry, throwing down an alley-oop on Paul Millsap and Kyrylo Fesenko. (Quick aside: Do the Jazz have a monopoly on huge Euro centers?) He also operated primarily inside in the first half and managed to get to the free throw line four times, which was more than he’s gone to the line in the last three games combined.

Again, it was a good night, but let’s give it another 10-15 games before we start to decide if KG is all the way back, and how good he is when he gets there.

“He’s coming along great,” Rivers said before the game. “He’s healthy. It takes time to get your timing back. I think he’s getting it, but it’s a process. He’ll be a far better player at the end of the year.”

And that’s really the only thing that matters.

SCORE ANOTHER ONE FOR RAJON RONDO

It didn’t have quite the sizzle of the Chris Paul matchup, or quite the end-to-end explosion of the Steve Nash game, but Rondo took the measure of Williams and came out far ahead.

There were mitigating factors, of course. Williams is battling injuries, and while he gamely gave it a go (Utah really didn’t have much choice as the Jazz were down to untested rookie Eric Maynor behind him), Rondo was far quicker and more aggressive than his counterpart.

“I’d like to move like that with a bad back,” Rivers joked. “But I think it was [bothering him]. You could see at times where he pulled up on the break. I mean, he wasn’t who he was, but he was pretty good at who he was tonight.” Rivers paused for a second, “Whatever I just said.”

That’s OK, Doc. We get your drift. Even limited, Williams still turned in a 13-point, seven-rebound, four assist performance, which wasn’t bad, but it wasn’t nearly as good as Rondo’s 14 points and 11 assists.

Rondo was able to get where he needed to go at will against Williams, who couldn’t keep him out of the paint.

But still, it was a good sign for Rondo, especially considering the old knock against him that he struggles against big point guards (a knock that he mostly put to rest last season). With Chauncey Billups and Jason Kidd in the latter third of their careers, Williams is the big guard heir apparent.

This was Rivers before the game on Williams, who is one of the most criminally overlooked players in the league:

“He’s one of the top two or three in the league in my opinion, and maybe number one. He’s got great size, speed. His shot is what sets him apart from some of the other guards. He’s a great shooter. He plays at different speeds. He’s the most powerful of the guards, him and Chauncey.

“His size is a factor, especially when he gets it going in motion. One of the things we do tell Rondo with him is his speed becomes his quickness. If you can somehow slow him down then you can use your speed. If you let him catch it on the run all day, you’re going to have problems. He’ll go through you, he’s just that strong.”

Rondo executed that part of the game plan perfectly. Utah had only two fastbreak points all night, and it was difficult for Williams to get up a head of steam while he was playing in a phone booth. 

So, score another one for Rondo, who continues to place himself in the upper tier of point guards.

ADJUSTMENTS WERE MADE ON THE GLASS

The Celtics are one of the worst offensive rebounding teams in the league. They are, however, one of the top defensive rebounding teams in the league.

The second part helps mitigate the first, but after 24 minutes of action the Jazz had pulled down 11 offensive rebounds, and that was a very big reason why they were still hanging around at halftime.

In the second half, the Celtics limited Utah’s second-chance opportunities, and not surprisingly, that’s when they began to pull away.

“The adjustment we made was to stop switching,” Rivers said. “We don’t switch. We kept switching in the first half and every time we switched, the guard who called switch ended up under the basket and the big was getting the rebound. In the second half we stopped switching and started doing what we should do. In defense of that, they are a difficult team not to switch on. They have so much movement down low with their bigs with their flex-action picks, then you get caught and you call switch.”

Interestingly enough, the Jazz were not real impressed with their own play on the boards. Williams called his team “soft,” while Sloan responded to a question about his big men thusly: “Well, I wouldn’t mind them rebounding. There ain’t any rules against them rebounding. I mean, if you’re just going to stay out there and shoot shots and not defend or rebound, it’s pretty tough. I thought we would try somebody else.”

That would probably explain why Carlos Boozer and Memo Okur played just eight combined minutes in the third quarter — and why Fesenko was on the court to get posterized by KG’s alley-oop. But that’s Utah’s problem.

The Celtics’ issue is that they have not had much success crashing the offensive glass, Wednesday night’s 12 boards notwithstanding. You can live with that if you’re holding things down on the defensive end, but if you’re looking for a weakness on this team, that would definitely qualify.