The Boston Celtics capped a vibes-filled preseason in the most Celtics way possible: Trotting out a starting five in which four players — likely bound for Maine and waived almost immediately after the team’s final preseason tuneup — toppled a Hall-of-Famer-filled starting five of the new-look Sixers, including old friend Jaylen Brown.

Boston produced a 4-0 preseason. Far more importantly, the team doubled down on an identity it started carving out last season and built around three main tenets: Be the hardest-playing team, win the margins, and do both those things regardless of the personnel combinations that Joe Mazzulla puts on the floor. 

There are still a bunch of lingering questions as the regular season arrives — we’ll tackle a few of those in a bit — but let’s start with five reasons for optimism as the Celtics prepare to dive into the 82-game grind. 

1. Jayson Tatum looks ready to be Jayson Tatum

Bob DeChiara-Imagn Images

Bob DeChiara-Imagn Images

If a longer-than-expected offseason had only one benefit, it is this: Jayson Tatum looks and sounds like he’s back to his old self. Tatum has admitted that he’s in a far better place, both mentally and physically, than when he first returned to action in March. Entering Year 10, and further removed from the Achilles injury that limited his availability last season, Tatum appears ready to shoulder the hefty load the team will heap upon him after its offseason changes.

Tatum checked all the preseason boxes. The scoring looked effortless. He shot the 3-pointer well (38.9 percent). He routinely generated quality looks for teammates. He was active on the glass. The stat line is going to pop this year. Tatum looked like a player who is ready to muscle back into the MVP conversation.

Tatum has always had a great appreciation for some of the stuff that NBA superstars eventually take for granted. He’s repeatedly noted this preseason how the uncertainty he faced a year ago has made him appreciate the minutiae of NBA life, including simply being on the court with his teammates throughout training camp.

"I think when you're sitting on the sideline for as long as he did, you kind of see the game a little bit differently,” said teammate Derrick White. "I just think that he's more confident. I thought he looked pretty good last year and so just getting that confidence, getting over the mental hurdle that everybody says is the toughest part about it.”

The bottom line: A healthy Tatum playing at an All-NBA level is the key to Boston remaining competitive in a beefed-up Eastern Conference. The early returns have been encouraging.

2. Hugo Gonzalez’s jumper could change the conversation

Winslow Townson-Imagn Images

Winslow Townson-Imagn Images

We resisted the urge to put this at No. 1.

Gonzalez finished 11-of-20 shooting (55 percent) from beyond the arc in four preseason appearances. That number should come back down to Earth a bit, but hopefully the confidence with which Gonzalez is chucking those triples will not. 

The release looks quicker. The confidence looks higher. Gonzalez shot 36.2 percent beyond the arc in his rookie season — right around league average — but being able to consistently knock down 3s is only going to help keep Gonzalez on the floor for a team overflowing with wing options. 

Still, we marvel at the confidence in preseason situations. Watching Gonzalez and buddy Baylor Scheierman shoot before training camp practices, Scheierman seemed to make everything he hoisted, while Gonzalez could be a bit more streaky. 

Then the games started, and Gonzalez thrived from distance. 

There was a sequence in the final Philadelphia meeting where Scheierman zipped a pass to the corner in transition and Gonzalez went straight into his shot. No hesitation. Just a confident catch-and-shoot 3 on his way to 21 points.

We already knew that Gonzalez will make good things happen on both ends with his activity. The lasting image from his rookie campaign was his willingness to go joust with Joel Embiid in Game 7 of a playoff series. Adding a dependable jumper will only make it easier for Mazzulla to keep Gonzalez on the floor. 

3. Paul George’s defense can make life easier on the offense

Bob DeChiara-Imagn Images

Bob DeChiara-Imagn Images

Doc Rivers made this point on a recent Celtics Talk Podcast: You might not fully appreciate how good George can be, defensively, until he’s on your team. The preseason offered a pretty convincing introduction.

George was a constant disruptor. Even at age 36, he’s active in passing lanes, routinely causing deflections and generating seven steals overall in two appearances. Even more importantly, Boston turned many of those takeaways into transition points. 

Generating some easy points off turnovers could be vital as the Celtics carve out an offensive identity without Brown. But the defense, overall, is intriguing considering how good the Celtics were on that end even before adding two guys like George and Mitchell Robinson. 

Slot George and Tatum at the forward spots, then add White doing All-Defense things at the guard position, and you can see the outline of an elite defense. Add in a Boston team that might be the best rebounding group in the NBA and things get real tough for opposing teams on the margins.

4. Payton Pritchard’s next jump might be as a playmaker

Eric Hartline-Imagn Images

Eric Hartline-Imagn Images

Pritchard said it himself before the season: Good things happen when you touch the paint. Watching him pile up 11 assists in a preseason game against Charlotte was a firm reminder.

We know Pritchard can score inside despite giving up size. But, going back through the tape, what stuck out was how often his penetration sucked in multiple defenders and created opportunities for teammates around him. 

Neemias Queta was a frequent beneficiary against Charlotte. That leaves us intrigued by how Mazzulla will deploy talent and how much that combo will play together. 

The Celtics need Pritchard’s scoring in the aftermath of Brown’s departure, but part of any leap he makes again this season could be tied to impacting the game even more as a playmaker. 

Maybe the best part is that Pritchard is setting a tone about roles, doubling down on his assertion that it doesn’t matter if he starts or comes off the bench, he simply wants to pile up minutes and impact winning.

“The starting conversation is kind of funny. To me, a starter is the amount of minutes you play,” said Pritchard. "Do you finish games? Are you playing 30-plus minutes? Then you are a starter.

"How do you impact the game is what really matters to me. I don’t really care — this might be an ego thing — I don't really care to hear my name called at the beginning of the game. The first five minutes of the game really have no effect on the game. So if that is what Joe thinks benefits our team the most, is me coming off the bench and playing those minutes, then I'm going to do it. And I'm going to try to be the best at those minutes. That’s my only thought process.”

5. Depth remains a Boston calling card … 

Tucker DeVries, Hayden Gray, Gabe McGlothan, and Milos Uzan were part of Boston’s starting five that toppled the Sixers. They were waived a few hours later with hopes they will all land in Maine as affiliated players.

But the success of the “red team” — the deepest reserves, most on Exhibit 10 contracts in camp — was a staunch reminder that Mazzulla can and will lean on depth throughout the roster. As his Game 7 lineup versus Philly showed last season, he won’t be afraid to mix and match as the situation requires. 

Which coincides with the second half of this optimism bullet point: 

… and the development pipeline has some intriguing projects

Rookie Chris Cenac Jr. is incredibly raw. But he's also still a teenager, and you can see all the potential to impact the game with his size, length, and athleticism. Both him and rookie two-way Dillon Mitchell ought to spend a lot of time with Maine this season, but those reps — and time behind the scenes in Boston’s player development factory — could be key in breeding future depth. 

Heck, even the Celtics’ assistant coaches got important reps this season with Mazzulla handing the head coaching reins to Tony Dobbins, DJ MacLeay, and Sam Cassell at various times this preseason. 

The Celtics are getting contributions from every player and coach on the roster. But now the real games begin and we’ll see if they can maintain the vibes.

The big questions going into the year: 

1. Can Boston stay healthy? 

Tatum missed Game 7 while still working his way back from the Achilles injury; George and fellow offseason addition Mitchell Robinson have to prove they can stay on the floor, even if the team will likely manage their overall workloads. Boston has the ability to lean into its depth, but it also needs to keep its main guys on the floor.

2. How does Mazzulla deploy his depth? 

Mazzulla has no shortage of options in how he crafts lineups. Robinson and Neemias Queta should eat the bulk of the 48 minutes at the center position, but who starts game to game could vary. The bigger question might be at the fifth starter spot. Does Mazzulla lean on a defensive-minded wing (like a Jordan Walsh who got multiple preseason starts with the core starters), or does someone like Baylor Scheierman or Sam Hauser elevate to that spot based on matchups. What combos give the bench the best ability to thrive?

3. How will Boston fill the Brown void?

Replacing Brown will be collaborative for the Celtics. Maybe Tatum gets a whole bunch more shots and fills much of the scoring void on his own. But no one can individually replace what Brown brought to both ends. And the team will have to morph a bit in his absence. Can George (or Pritchard or White) be strong secondary scoring options on nights that Tatum is either struggling or defenses are blanketing? Brown routinely loved taking on the challenge of defending the opposing team’s top scoring options. Even on Day 1 against Cade Cunningham and the Pistons, who takes on the lion’s share of that defensive assignment? 

Answers are coming soon. After nearly six months, it’s finally time for real basketball in Boston again.