Sean McDermott said Stefon Diggs was not at mandatory minicamp with the Buffalo Bills on Tuesday.

McDermott called Diggs' absence "very concerning" before Tuesday's minicamp practice. Diggs had missed voluntary workouts.

Diggs' agent, Adisa Bakari, told ESPN's Adam Schefter that his client is in Buffalo and has been there since Monday morning. He said Diggs took his physical, met with McDermott and general manager Brandon Beane the past two days and "will be there for the entirety of the minicamp."

The wide receiver signed a four-year, $96 million extension last offseason, and trading him would incur a significant dead cap hit, including $13.2 million this year.