Grigson was the Eagles director of player personnel before being hired in January 2012 by the Colts.
Gamble has worked in the NFL since entering the league as an assistant in the Eagles personnel department in 1988.
Roseman, 37, who joined the Eagles in 2000 and was promoted to general manager in January 2010, has considerably less NFL experience than Gamble. That brought the inevitable questions as to whether the hiring would mean less personnel power for the general manager.
Roseman said the Eagles will continue to operate the same way, using a collective effort to build the team.
"To get where you need, you can't have egos, and it's not going to be about who is my player, who is Tom's player," Roseman said.
Roseman said having Gamble did allow him to concentrate on some of the other general manager duties.
"Your vice president of player personnel can watch 350 players and then narrow it down when it gets to the general manager," Roseman said. "Having guys you trust to narrow it down does allow you to do other things."
Roseman said that the Eagles had talked to Gamble last year after Grigson left but indicated that Gamble wasn't ready to make a move
"He has three boys, and family is a big concern, and he wanted to make sure the timing was right," Roseman said.
This year was a different story. Gamble had interviewed for a few general manager jobs, and he has a strong reputation around the NFL.
Roseman added that before hiring Gamble that the Eagles spoke to other candidates but were impressed by Gamble's extensive experience and success.
"He had a great run in San Francisco, and they have been very successful over the last few years," Roseman.
During his first stint with the Eagles, the younger Gamble served a variety of roles through 1994, including college scouting administrator, area scout, contract negotiator and later as director of pro scouting.
He worked for the New York Jets as a defensive assistant/quality control coach from 1995-96 and was a pro scout for the Baltimore Ravens in 1997. Gamble joined the Colts as a college scout from 1998-2004 before joining the 49ers.
Contact Marc Narducci at firstname.lastname@example.org or @sjnard on Twitter.