It appears the team released McDonald in order to make room on the 90-man roster for another center.
According to Michael Gehlken of U-T San Diego, the Chargers agreed to terms with undrafted rookie free agent center Khalil Wilkes. The team has not confirmed this report.
At 6-foot-3 and 285 pounds, the Stanford product attended San Diego’s rookie minicamp in May after the draft as a tryout player.
Wilkes earned second-team, All-Pac 12 honors last season, and played in the East-West All-Star game.
When the Wilkes’ signing becomes official, the Chargers will have 15 offensive linemen on the roster heading into the start of training camp on Thursday, and five players with experience snapping the football in Nick Hardwick, Rich Orhnberger, Chris Watt, Johnnie Troutman and Wilkes.