This roster is better then the 2019 team that went to game 7 of the cup
This team is a legit contender
This doesn't account for Father Time. Bergeron is 37, Krejci 36 and with a year out of the NHL. Bergy, for all his undoubted continuing defensive prowess, no longer has quite the offensive impact he once had. He got beaten by Staal in the first round last season. Hurts to say it as a Bs fan, but it's the truth and it was an important factor in the Canes' victory. The Islanders muted him the year before too. As for Krej, we hope he can get back to something near his best, but that's no certainty. Regardless, these guys are not who they were 3 years ago. At their age, they just can't be. Then you have Marchand returning from double hip surgery. Again that's not easy, especially at 34. Hopefully like Krej he turns out completely fine. But we will see.
On the flip side of course, you have Pasta, McAvoy and DeBrusk all older and more experienced. But is Pasta better than he was in 2019? I'm not sure he is. He's great, but I feel like he might be one who peaked early and is now just going to hold that admittedly very high level. Chucky is better for sure, DeBrusk has shown he can be if he can hold his form of late last year, but he still needs to prove he can be consistent.
Elsewhere on the roster, Hall is of course a big gain. 3rd line Zacha-Coyle-Smith or something like it replaces Johansson-Coyle-Heinen. The current unit has the potential to be better but Zacha still has to prove it at his new club, and Coyle and Smith need to rediscover their best form. Smith in particular is coming off a disappointing season and Coyle has never quite recaptured his 2019-20 performance. 4th line is very much wait and see, but Kuraly-Acciari-Wags/Nordy was a very very capable unit in 2019, and finding a combo that can play at their level or better will not be easy.
Defense, Lindholm for Chara, of course. Very different styles, but in talent level it's pretty like for like. Krug is gone and nobody else on this team packs his offensive punch, especially on the PP. Carlo in theory should be better but because of his head issues so far he has not been. Huge question mark there. Clifton and Gryz are still here. Cliffy is better, Gryz is Gryz. Instead of Miller and Moore you have Forbort, Reilly and Zboril, which is a bit of a wash.
Put that all together and I do think the current roster at its best could match it with the 2019 one. Better? I doubt it. But competitive, I think so. BUT you're relying on a lot to go the Bruins' way to get there. 37 & 46 defying time and injury, Marchand completely recovering, DeBrusk maintaining the rage, all 3 of the 3rd line coming good, finding a 4th that works, Carlo sorting his head out, and the defense in general both driving enough offense from the back end and proving tough enough in their own zone. There's a very good team in there, but it's going to need a lot of hard work and not a little luck to really show itself.
Edit: forgot to mention the all-important goalie situation. Swayman is a good'un, and should continue to improve, but he is no peak Rask yet. Don't see it as a weakness, but it is another TBC.