A 2009 third-round pick, McKenzie was waived by the team on Sunday to make room for veteran linebacker Tracy White, who is considered a strong special teams player.
Had McKenzie been waived one day earlier, he could have had a greater chance of being claimed by another team. But with most teams setting their 53-man rosters and shifting their preparations for the season opener into a higher gear, McKenzie slipped through.
James (6-0, 215) played in college at Miami, where he finished his career with 2,162 yards and 18 touchdowns. He had signed with the Colts after going undrafted.
Mastrud (6-6, 253) played in college at Kansas State, where he played in 48 games and set the school record for total receiving yards from a tight end (1,219). He had signed with the Buccaneers after going undrafted.
The Patriots now have seven players on their practice squad and can fill one more slot. With just two quarterbacks on the 53-man roster, the team would presumably like to add another player at the position, on the practice squad.
Mike Reiss covers the Patriots for ESPNBoston.com. Follow him on Twitter.