I guess it really depends on how we define better. Some have mentioned some areas, like regular season record, others more subjective criteria, but even those who think they won't be "better" have said they will still win the Championship. If that is the criteria, then the Celtics cannot be better by definition, only as good. Does it really matter to split hairs about the impact of Posey's departure, and if those vying to replace that production and role will be able to if the ultimate conclusion is that they will win it all again? Everything else is pure speculation, I know the self-appointed experts here like to presume what absolutely will and will not happen, but I think any measured review of last year did not yield an overwhelmingly positive response that Pose and the bench were 100% solid, no question marks, the clear formula to win it all, at the beginning of the year. We know now they did win, but it is something else to say it was widely assumed the mix off the bench last year was just right ahead of time.
I understand the OPs point in terms of an injection of youth that is vital to an "older" team that the Celtics are called all the time now. The experience factor has been somewhat lessened as a need off the bench specifically because of what happened last year, all the returnees have vital experience now, neutralizing the lack of that by some key bench pieces. It is a long regular season, as Doug Collins often says, a deep bench is the most important in terms of getting the starters rested for the playoffs. Pose and House stepped up big in some key spots in the playoffs for sure, but there were long stretches during the first 82, people only remember the last 6-26 it seems, where the 2nd unit was downright anemic in getting anything going on offense. A bunch of guys standing around, spotting up, but with no creators to distribute to them, it forced Doc to keep at least one of the Big 3, often Ray or PP, out there all the time to counteract that, playing them more than he would have liked. This year's bench has more potential in that area, not as proven, no, not as clutch, no, but as stated, we can get that from a host of places now and that is not as critical in terms of bench play until much later in the year, plenty of time for that to be sorted out. In terms of being a viable, flexible unit that can defend and score, that can provide more rest this year than last to the Big 3 so that they are fresh for the playoffs, the bench is more capable this year in my opinion.