On Poteat: The guy just shows up and plays. I know he's not a big-play corner - in a five-year career, he has zero interceptions. But he's a solid tackler and picks up the coverage well. Sorry to see him go. With Dillon, Maroney, Faulk, and Evans, I'd rather have Poteat than Pass.
On Sullivan: Good riddance. He was given every chance to gain a spot in pre-season. He got plenty of time on the field, and we know how the Pats love big defensive linemen. With the physical talents of a top ten draft pick, he was unable to beat out Mike Wright -- or Le Kevin Smith, for that matter. If another roster spot is needed, I assume they'll start searching for Marquise Hill's locker.
On Gaffney: Sounds like an upgrade over Bam Childress of Kelvin Kight as a fifth receiver. It is one more guy who doesn't know the Patriots playbook. The results of bringing in guys like JJ Stokes at this point in the season is bleak. And he could possibly take bye-week rotations away from Jackson and Gabriel. But as a fifth receiver, someone to learn the system for a couple weeks and come in for injuries, he'll be OK.
On Pass: As noted, there is so much depth at RB right now, there's no need to 'rush' him off the PUP list - he has weeks six through nine to come off. His more important contribution would be on special teams. While he is a below-average kick returner, he's OK on kick coverages. I don't see a big need for his type on kick coverage - Alexander is excelling, Davis and Izzo are a little above average.