Regarding the Patriots:
The NFL is a year to year league. I think the Patriots next season are not going to be a last-place team. Unless he's changed, I think Vrabel is solid as a coach. He brings discipline. He does thorough game prep for opponents and plans well to exploit the tendencies he sees.
I don't know how good they'll be. I think Drake Maye has a lot of potential. I'm skeptical of Josh McDaniel as an offensive coordinator. There are some QB where he seems to bring out the best, and there are some QB where it seems as though they just can't execute his offense, though they can function adequately or even well under other OCs.
Regarding Diggs:
By the end of his last year in Buffalo, Greg Cosell (who watches A LOT of film) was saying that Diggs at that point no longer had the physical abilities of a #1 WR in the NFL. Maybe he was; the issue with Diggs in Buffalo his last 2 years here seemed to be fading down the stretch and disappearing in the playoffs. I think it's not uncommon as a player gets older, he can still play and come into the season strong, but it's harder to maintain a high level throughout the full season as the dings and dents mount up. That's the pattern the Bills saw in 2022 and 2023: a strong start to the season with multiple 100 yd games through wk 8 or 9, then falling off a cliff.
Certainly the Texans didn't trade for Diggs and then re-negotiate his contract to shorten it and pay him more because they agreed with Cosell. But they lost their gamble when Diggs went out with the ACL after Week 8, so we'll never know if he would have done the same "falling off a cliff" move in a full season with them.
I don't think Diggs is gonna be ready to play until the middle of the season. It'll be interesting to see how he goes.