http://www.denverpost.com/broncos/ci...cos?source=pkg
This article does state that Ramirez did work at Center during offseason workouts, prior to training camp.
But it also says he gave up 6 sacks in one on one situations last year, the highest on the team.
Manny Ramirez, who made 11 starts at right guard for Denver last year, was at center throughout offseason workouts before training camp. But when Walton was forced to have more surgery, Denver signed Koppen and he was quickly put into the starting lineup.
Ramirez, a powerful blocker in the running game, allowed six sacks in man-on-man situations last season, the highest total on the team. Many defensive coordinators in the NFL say the best way to unsettle quarterback Peyton Manning is with pressure up the middle, so any issues at center would certainly impact the Denver offense.