I admittedly don't have the numbers or stats to back this up, this is just purely based on the eye test. But you know something that feels notably different compared to last year when I see the team play?
They are just younger and much faster/quicker on the court.
Yes the C's 1000% lost a lot of talent in Porzingis/Horford/Jrue, that's undeniable and they still haven't replaced them all. But lets also be honest, 2024 was an amazing ride but the C's still won the Finals with Porzingis missing 70% of the playoff run, and frankly even in 2025 Horford and Jrue just seemed to get noticeably slower (due to age) and Porzingis was still unreliable from a health standpoint.
Knock on wood, so far this team has mostly stayed healthy and durable including Jaylen, and yeah the pace of play is just so much faster compared to last year and I think that's also contributing to the hustle and winning plays. The C's offense is also rated highly in a lot of areas and scoring a lot, which is another byproduct of it.
They are quick in transition, move up and down the court fast and are able to mostly keep up on the defensive end even if the other team tries to "outrun" them or use their young athleticism.