The one thing you cannot escape about Diggs is he has a tendency to disappear late in the season and in the playoffs. Bills fans will tell you this.
He had 110 yards and one TD in four playoff games last year. By comparison, Boutte had 168 yards and a TD, Hollins had 129 yards and TD (and he was coming in off of being on IR), Hunter Henry had 112 yards and TD, Stevenson had 126 yards receiving and a TD, Pop Douglas had 84 yards and a TD. So after being the clear #1 Maye target in the regular season, he finished fifth in yards in the playoffs. No receiver wrapped themselves in glory, but no one fell more than Diggs in the playoffs.
I am guessing that is a big reason why the Pats did not retain Diggs. And at his age, the chances of him slowing down in the playoffs get greater and greater.
Doubs isn't as good as Diggs, but if he hits as a free agent he is far more likely to carry regular season success into the playoffs than Diggs is at this point.
After last year with everyone questioning the acquisitions of guys like Tonga, Chaisson, Durden (more of people just dismissing his acquistion as just roster fodder), and overpaying for Williams. I give the Pats brain trust the latitude to give them a chance to prove that moving on from Diggs and adding Doubs was the right move.