With Ryan Pace's pieces in place, the challenge now begins for Matt Nagy

Bears hit the upgrade button and overhaul wide receiversRyan Pace isn’t in a position to feel satisfied with the improvements made to the Bears’ roster around quarterback Mitch Trubisky, not until some actual, tangible success comes from his efforts.

But the fourth-year general manager went into this offseason needing to improve the structure around his prized quarterback. It started with hiring Matt Nagy and a quarterback-driven offensive coaching staff, and continued with a barrage of free agent signings and then a pair of second-round draft picks.

“I know we were aggressive,” Pace said. “We knew we were going to be. But again I don’t just feel like we’re ever there. There’s still things we…