The team allocated financial resources in free agency to sign defensive ends Jared Allen, Lamarr Houston and Willie Young, plus re-signed cornerbacks Charles Tillman and Tim Jennings and defensive tackle Jeremiah Ratliff.
Marshall's $30 million extension came four months after the Bears agreed to a lucrative new deal with quarterback Jay Cutler.
"Phil Emery and the guys upstairs have done an amazing job, not just this year, but also last year," Marshall said Tuesday on "The Carmen & Jurko Show" on ESPN Chicago 1000. "What they've done on the offensive side and how they revamped the offensive line in one draft and one free agency [is impressive]. Now they are doing the same on the defensive side.
"Change isn't unique in the NFL. We've had a lot of change here in the last few years, and I think guys in the whole building adjusted well to it. It says a lot about the whole culture the McCaskeys and Coach [Lovie] Smith had created here. The guys like Brian Urlacher and Lance Briggs have been amazing. We're just trying to carry the torch."
Marshall and a large number of his offensive teammates spent a portion of the offseason training together in South Florida, where the wide receiver has a home.
"That's the way to win in modern sports; it's not really what you do on the field or during the season, it's what you do off the field away from the sport," Marshall said. "We are not talking about the training in the offseason; we are talking about getting together and building that chemistry and authentic relationships.
"It's going to be awesome to see us grow because of the experience and the time we've been able to put in throughout the offseason."