The Patriots currently have one open spot on their 90-man roster, and there is no reason to think that it won't be filled. Bill Belichick often talks about maximizing opportunities and it does the Patriots no good to leave the spot vacant.
With this in mind, let's talk out loud about which direction the team might go.
At this point of the offseason, with organized team activities set to begin May 20-21, Belichick likely has practice on his mind with the 90th spot. Specifically, which areas look a bit light when factoring in players managing injuries, as well as the desired number of players at each position?
A little more experience at center/guard looks like the sweet spot, with starting right guard Dan Connolly having undergone offseason shoulder surgery, and the Patriots not using a draft pick at those positions.
So it wouldn't be a surprise from this viewpoint if the Patriots follow up Thursday's workouts of Rex Hadnot (10th season) and Antoine Caldwell (5th season) by signing one of them. Both have ties to Belichick confidant Nick Saban -- Hadnot having played for him with the Dolphins, and Caldwell having played for him at Alabama. Hadnot also played under current Patriots assistant coach Brian Daboll for one season with the Browns (2009).
Whichever player looks the best at center, and is in the best condition at this time, would have the edge from this viewpoint. I heard good things on Hadnot's workout, so I wouldn't be surprised if he's the choice.