The Buffalo Bills have been busy this week adding to their pre-draft visit total. On Tuesday several big-name defenders visited One Bills Drive but later in the week some potential later round prospects made the rounds at Orchard Park.

Aaron Wilson of the National Football Post is reporting the Bills met with Arizona center Colin Baxter but doesn't specify when that meeting may have taken place. Also confirmed to have been at the Bills facility on Thursday this past week were Iowa DE Christian Ballard and North Carolina OLB Bruce Carter.

Baxter is recovering from a knee injury and is considered an undrafted prospect unless a team takes a late-round flier on the otherwise durable center. To his credit Baxter was a finalist for the Rimington Award in 2010, given to the nation's top center.

The scheme-versatile Ballard had a great Senior Bowl and would be a target for the Bills in the second round. Carter tore his ACL in December and hasn't worked out for teams but could still be a late second round pick based on his fine career as a Tar Heel. Carter's visit likely included a look at that knee to see how it is progressing.

Based on our count from various sources the Bills have now had 20 visitors. Here's a breakdown:

• Seven defensive linemen: Da'Quan Bowers, Cameron Jordan, Marcell Dareus, Nick Fairley, J.J. Watt,  Robert Quinn, and Christian Ballard
  
• Three quarterbacks: Cam Newton, Blaine Gabbert and Christian Ponder
• Five pass rushers: Von Miller, Ryan Kerrigan, Justin Houston, Brooks Reed, and Bruce Carter
  
• Two inside linebackers: Kelvin Sheppard and Quan Sturdivant
• One offensive tackle: Gabe Carimi
• One center: Colin Baxter
  
• One cornerback: Patrick Peterson