While McDermott did not elaborate on the length of either player's absence, NFL Network Insider Ian Rapoport reported Monday morning that Matthews is expected to miss about one month.
Matthews scored his first touchdown of the season in Sunday's 23-17 victory over the Atlanta Falcons. The 25-year-old has 10 receptions for 162 yards in four games for the Bills (3-1).
Rookie Zay Jones, fellow wide receiver Andre Holmes and tight end Charles Clay likely will see an increase in workload in the absence of Matthews.
Humber has recorded a team-leading 37 tackles in four games this season for Buffalo.
The 30-year-old Humber was replaced in Sunday's contest by rookie Matt Milano, a fifth-round pick out of Boston College.