PHILADELPHIA -- One follow-up from the Patriots' joint practice with the Eagles on Wednesday was at the No. 4 safety spot.

Second-year man Tavon Wilson was out. Rookie Duron Harmon was in.

It is always dangerous to read too much into one practice, or one breakdown like Wilson had Tuesday when he appeared to make an error on a long touchdown pass (we also saw that twice from Wilson during his 2012 rookie season).

At the same time, Harmon's presence provided an opportunity to watch him against better competition, and learn more about his style of play.

He seems to have good instincts, and when the football is thrown in his direction, good ball skills. At 6-foot-1 and 205 pounds, his movement skills seem more fluid than 6-foot, 215-pound Wilson's.

Safety Devin McCourty was asked about Harmon after Wednesday's practice.

"He’s working hard. He’s learning the system. I like being in there with him," McCourty said. "Even if he’s unsure about something, he’s usually moving in the right direction; you tell him one thing and he puts the pieces together and he’s out there. I’m encouraged by the effort and the time he puts in.”

McCourty is locked into one starting safety spot, with a competition unfolding between Adrian Wilson (6-3, 230) and Steve Gregory (5-11, 200) for the spot next to him. Wilson offers a bigger, more physical presence, while Gregory is the better coverage player.

Harmon, Wilson and special-teamer Nate Ebner are next up on the depth chart. On Wednesday, it was a chance to take a closer look at Harmon.