Williams, 28, is a 2008 first-round pick out of Chicago who flamed out there, then resurrected his career a bit over the past two seasons with the St. Louis Rams. He started all 16 games for the Rams at left guard last season, and you can safely pencil him in as the Bills' starting left guard heading into the 2014 season.
Why, you ask? Because Williams' contract is nearly as large as the four-year, $15 million deal that Kraig Urbik signed in December of 2012 to continue to play right guard for the Bills. The signing relegates veteran Doug Legursky, who is still under contract for the 2014 season, to a likely reserve role as a backup center and guard.
The Bills are also hosting free agent cornerback Nolan Carroll at One Bills Drive today; he'd made his visit alongside Williams, who is signing on the dotted line.