I've been thinking about it, and here's my theory that I was trying to articulate earlier, but was rushed.
I think there were basically 4 bubble players when the roster went from 80 to 53: Meriweather, Warren, Butler, and "TE" (Smith/Yeatman). The prevailing theory when cuts were made was that Meriweather was a legit cut, Warren and Butler made the team, and that the Pats were hoping to keep Yeatman/Smith on the practice squad. Under this theory, the Pats would be planning to go into week 1 with 2 active tight ends. However, if they were planning on going into week 1 with 2 tight ends, they would not have cut a player just to make room for Gronk II on the active roster; if they were planning on 2 tight ends for week 1 they would have just added the tight end to the practice squad to take the place of Smith/Yeatman on the squad. However, adding a new TE to the 53 roster for week 1 seems to pretty strongly say that they wanted 3 TE's on the roster, but that Yeatman/Smith weren't good enough to be that player. In other words, the clear preference was for 3 TE's, but the 'value' of keeping Warren/Butler on the team at that time was higher than keeping a bad player like Yeatman/Smith just to be the token 3rd TE. I think bellichek has clearly shown that he'd rather keep a player who can contribute at a duplicate position over keeping a player who he thinks can't contribute, even at a position of need. However, when a player became available (Gronk II) that they thought could actually be a valuable 3rd TE, they then cut one of the other bubble players to add him. After all, if Yeatman/Smith were worthwhile 3rd TE's they would have cut Butler/Warren to keep them, and they wouldn't have cut Warren/Butler to add a 3rd TE if they just wanted 2 active TE's and 1 practice squad TE.
As for the other signing, i'd guess that they felt they had adequate Corner depth, and adequate Defensive Tackle depth, and made a value/upside signing. Guy sounds like a smart player who could probably play some hybrid positions.