The Celtics completed their second week of training camp and their first three preseason games with only a peek of new talents Jrue Holiday and Kristaps Porziis playing alongside Jaylen Brown and Jayson Tatum. The last two sat on Monday and Wednesday, with an unusual three games in four days effectively splitting the team into two camps. On Thursday, Boston returns to action one week before the season opening against the Knicks, who may rest on the front half of a back-to-back, and the Hornets in Charlotte.

Here’s what I’ve noticed thus far from observing camp and practice:

Sam Cassell seemed to be an asset to Jayson Tatum, sitting on the bench with him when Tatum rested the last two games and pressing him to play physically in the post during shooting practices at Boston’s facility. Tatum described Cassell as the loudest person he’s ever met, even louder than Grant Williams, while Joe Mazzulla stated that their collaboration came effortlessly. Cassell also worked with Dalano Banton, the team’s emerging point guard, this week and will spend time with Jaylen Brown as the team’s talented wings continue to refine their playmaking.

“I simply inquired if that was what (Tatum) desired.” “During my first couple of years in the league, Sam worked with (Tyrese) Maxey and had the same shooting time as our guys, so I was always able to observe what Sam was doing pre-game with Maxey and some of the other players,” Mazzulla explained. “Just talking to Sam, talking to Doc (Rivers) about what Doc relied on Sam for and what he was able to do during the hiring process, it just made the most sense.” Sam has also been through every situation in the game and has worked with players both on and off the court… We need him to do one-on-one interactions with Jaylen as often as he works with Jayson… Sam has simply been around for a long time, and because of his knowledge, really talented coaches have relied on him to navigate the squad… It was simple, (Doc explained), if you don’t hire him, someone else will… It was an obvious choice.”

Jaylen Brown was visibly toned after working shirtless with Tony Dobbins after practice, spending time in the weight room with trainers, and lately posting some of his core work. A social media video of him awkwardly dribbling lefty caused a sensation, and perhaps some reckoning on the social staff. In the opener against Philadelphia, he struggled to make dump-off passes out of the lane, and all eyes will be on his ball-handling after a playoff low point in Game 7 against Miami. His pledge to focus on defense intrigues me, and Mazzulla stated that no one holds Brown to a higher standard than himself. He may have to acclimatize to the oncoming stars more than anybody else, but Porziis’ presence should aid his reads.

Could Jrue Holiday make an appearance off the bench? Zach Lowe, Tim Bontemps, and Jake Fischer all discussed it on podcasts, so my brow furrowed, but Mazzulla has already hinted that the team will start multiple units to open games, and it sounds like he’s preparing some players who generally start games to remain flexible. For the first time this week, Al Horford revealed willingness to do so, and he said others are as well. Holiday had not discussed his role since arriving in Philadelphia on Wednesday. Derrick White will be the easiest to sit, as he is open to any role or minute allotment. Mazzulla may lean in that route more often than not, but another great defensive performance against Philadelphia demonstrates his strength.

When Boston starts Horford and Porziis, Luke Kornet still appears to be the backup center, and it’s worth noting that he’s collaborating with new second unit players battling for minutes and roster places. Kornet’s pivotal role with the bus one youngsters, who frequently won their minutes and nearly beat the Bucks at full strength, instills trust in him. Despite only 11 points, six rebounds, and two blocks in three games, Mazzulla has commended his efforts on both ends. Check out his assists — three in each of the last two games — and you’ll understand why he’s still a lock to play. It’s difficult to say how much Neemias Queta has closed the deficit with great performances in the last two games. Mazzulla stated that he received more minutes this week, but the seven-footer who dominated the G-League one year faced identical back-of-the-bench competition. He plays with more fluidity than I thought, but he gets fouled frequently – five times in 14 minutes in New York.

Mazzulla admires Banton, and the Knicks game demonstrated why. He can defend wings, has experience in a variety of defensive systems, and primarily plays point guard on offense. The shooting isn’t terrific (2-for-9 through three games), but his eight-week acclimatization to the team’s screening game in Boston over the summer prepares him well for a shot. He’s the favorite among newcomers for early backup wing minutes, trailing just Sam Hauser, who remains the greatest bet to play off the bench behind Brown and Tatum.

Lamar Stevens and his trainer, Henry Woo Jr., are optimistic about the training camp invite’s chances of making the roster following the Jrue Holiday deal. Stevens told me he could even play small ball center for the Celtics, and his five three-point attempts in New York were a career best.

Holiday looks great after practice, and Charles Lee, his former assistant in Milwaukee who is now Boston’s associate head coach, has been challenging him. Holiday’s arduous week, which saw him go from Milwaukee to Portland to Boston in two trades, reminded me of White’s difficult transition to Boston in 2022. Will Holiday struggle to adjust to his new role with the Celtics?

Despite the efforts of great veterans like Horford, Jordan Walsh sounds Maine-bound in November.

What a letdown for Jay Scrubb, who tore his ACL last week and will almost certainly be released from his two-way contract. D.J. Steward, who has been with the club throughout camp, is a possible replacement.

I’ve enjoyed hearing Porziis talk about his background, confessing to some stupidity during his early NBA career. He already made some sacrifices in his extension, and he challenges his Celtics colleagues to do the same on the floor. His shot blows me away, a lightning-quick release, and he’s just 7-3 with arms that seem to go on forever. This week, Mazzulla and Horford praised his defense, and his integration into Boston’s attack was easy in his first two games. If he stays healthy, he should have a monster season.