in the Chargers' lost 2016 season he had some pretty impressive game splits, even though he didn't get to play much he had over 800 yards.
Inman is way better than Brice Butler, though I get your point, Butler was very limited on the route tree (outside receiver only; good at only streaks and comebacks which made him easier to defend) but that's in part because his agility was limited compared to Inman's.
Inman is 30 so he's not going to make the HOF but he had that level of talent if he had been in the right system. If he makes the Pats he's going to be their best receiver in due time, could see the biggest numbers they've had since Cooks or even Moss.
As far as the Pats go in general, I think they have a league-average roster talent wise (12-17 range) but you could say that about them last year as well even with Gronk, or in 2016 when Gronk went out... they have by far the best coaches in the league (HC, OC, OL coach) so they'll make it work and almost certainly be the #1 seed considering KC is taking a big step backward without Hill and the Browns are just too young to be the best team in the AFC.