BOSTON — The NBA season began where it ended last summer — inside TD Garden, and a rather quiet building, too, after the Warriors closed out the Celtics in six games.

The good news for the Celtics this time? Stephen Curry was clear across the country playing in another game. So the task became easier for the home team, then, if only for that reason. Also, unlike that game, the Celtics showed up Tuesday and played a full 48 minutes and sent an early season message to the Sixers, one of a handful of teams seeking to take the conference away from the defending East champs.

Here are the five takeaways from Celtics 126, Sixers 117:

 1. Jayson Tatum strikes back

There were two players in this game that had to shake a shaky last impression from a season ago — and we’ll get to James Harden in a minute. Last we saw Tatum, he was tossing bricks in the 2022 NBA Finals and coming up short in performance and energy against the Warriors. He spent the rest of the summer trying to come to grips with that, especially since he was so solid during a regular season that saw him take a superstar turn and make All-NBA.

There’s really nothing he can do to totally restore the shine until next spring in the playoffs, but another superb season will put him in the right frame of mind, and he’s off to a good start in that regard. Tatum had some terrific transitional moments against Philly where he made defensive stops and followed up with jumpers and layups, especially in the game-changing third quarter when the balance flipped to Boston.

Tatum finished with a feel-good performance: 35 points (matching Jaylen Brown’s 35) and 12 rebounds, perhaps a tone-setter for him in 2022-23 — and maybe beyond. This was a confidence-booster game for him. By the way, Brown and Tatum have each had 30-plus points in the same regular season game 13 times in their careers together.

2. Harden mimics Houston Harden for a change

James Harden turned in an impressive opener, scoring 35 points on an efficient 9-for-14 shooting.

By every reasonable metric, Harden’s first stint with the Sixers was a letdown. He arrived in midseason from Brooklyn and the initial expectations were just too steep and maybe unrealistic. Yes, he was replacing Ben Simmons and that alone was an upgrade at least offensively. But Harden was astonishingly (for him) inefficient as a shooter, yielded too often to Joel Embiid, and was a skeleton of the Kia MVP who ruled the scoring charts with the Rockets. He also wasn’t in the greatest of shape, either.

Finally, he flamed out totally in the playoffs for the Sixers, getting just 11 points. He reset over the summer, reduced weight, signed a team-friendly contract extension that allowed the Sixers to add other players and came to camp feeling determined. Harden said his purpose this season won’t be to score a bunch as he did in Houston — he probably couldn’t anyway — but to get others involved and make more of an impact across the board.

Then in the opener against the Celtics, he had to score somewhat out of necessity, and delivered 35 points on 9-for-14 shooting, with 16 points in the first quarter and 22 by halftime, mainly by drawing fouls as frequently as he did in his prime. His previous high with the Sixers was “only” 32 points. Also, he was guarded Tuesday by Marcus Smart, the reigning Kia Defensive Player of the Year. The Sixers hope they won’t need Harden to score 30-plus a night, but it’ll be reassuring if he can do that in a pinch.

3. Celtics need to come up big

Starting center Robert Williams is out for about another two months because of lingering knee issues. It’s an inconvenience at best, and a big loss at worst, for Boston as the Celtics make do until then. Plenty will rest on the shoulders of Al Horford, who had some turn-back-the-clock moments last season in his second stint in Boston. But Horford is 36 and the Celtics are rather thin at the power positions. It made for an interesting test case against Embiid, who led the league in scoring last season and, for the second time, was runner-up in the Kia MVP voting. Embiid did have 26 points and 15 rebounds, but didn’t exactly cause the level of damage against the Celtics that those numbers might indicate.

Not only did Horford do a credible job, but the Celtics received decent minutes from Noah Vonleh, the journeyman (and temporary) backup. How the Celtics do without Williams could determine where they’ll place in the East. They’ll see Embiid again, not to mention Giannis Antetokounmpo, Bam Adebayo and the young Cleveland bigs as well.

4. Sixers’ missing pieces were, well, missing

When Harden agreed to take a cut in salary, he did so with the purpose of helping Philly strengthen the rotation. PJ Tucker, Danuel House, Montrezl Harrell and De’Anthony Melton arrived to place the proper ingredients around the nucleus of Embiid and Harden. Mainly, they’re charged with spreading the floor on offense and providing an extra layer of grit on defense. Anyway, one game into the season is hardly enough time to measure anyone’s worth, but it wasn’t the best of impressions. None of the three were major factors in the loss to the Celtics.

Harrell collected fouls, House didn’t make a basket and Tucker couldn’t stop either Tatum or Brown, both of whom scored 35 points. At least the three, unlike Harden in 2021-22, will have an entire season to prove their worth. Tucker does bring the toughness the Sixers crave, while House should take advantage of having open looks with Harden and Embiid drawing extra attention. As for Melton, he wasn’t involved in the offense and was mainly invisible in his 21 minutes, finishing with five points and a minus-13. They will all need to be at their best when the Sixers are matched against the East powers. If not, the Sixers might be a few pieces shy of a championship load.

5. Blake Griffin in a Celtics uniform is, well, weird

Sporting No. 91, Blake Griffin finished with 5 rebounds in 8 minutes in his Celtics’ regular-season debut.

And not just that, he wore No. 91, not the most common of choices. It just made for a surreal sight, how a player who once won a dunk contest by jumping over a car is now reduced to being a role player trying to hang on in the league. A fair number of players who played at the same level of Griffin wouldn’t stick around for this. Too much pride would tell them to retire and count their money. So give Griffin this much — his love for the game obviously remains strong.

At his height with the Clippers, and before the multiple knee surgeries, Griffin was an All-Star and franchise player who, just two years ago, was making max money ($35 million). Now he’s at the vet minimum and setting screens. He can’t jump or move as quickly; that is apparent. And you wonder how much time he’ll see as the season progresses. It’s quite a comedown both financially, in role, and in terms of reputation. He did get five rebounds in his eight minutes, but that’s the point — eight minutes for a star who once commanded so much more.

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Shaun Powell has covered the NBA for more than 25 years. You can e-mail him here, find his archive here and follow him on Twitter.

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