Miami Dolphins CB Mackensie Alexander placed on season-ending IR with undisclosed injury 10:54 AM ET Marcel Louis-JacquesESPN MIAMI -- The Dolphins placed cornerback Mackensie Alexander on injured reserve Tuesday, ending his season one week after he signed with the team. Alexander was injured in Miami's preseason game against the Las Vegas Raiders on Saturday, but Dolphins coach Mike McDaniel indicated he didn't believe there was reason for concern following the game. After further medical evaluations, however, it became apparent that McKenzie's injury was more severe than anticipated. "That was unfortunate -- really unfortunate for him, specifically, because we just got him and he was doing some good work out there," McDaniel said Tuesday. Alexander's placement on injured reserve means he will miss the 2022 season -- unless he's released with an injury settlement. Miami signed Alexander as a replacement for Trill Williams , who tore an ACL during the team's first preseason game. The Dolphins are already without starter Byron Jones , who remains on the physically unable to perform list after offseason Achilles/ankle surgery. Cornerbacks Nik Needham and Keion Crossen were also injured in Saturday's game; McDaniel said Needham is "good to go," while Crossen is considered "day-to-day," and the team will take things slowly with him. Miami's cornerbacks room still features a healthy former first-round pick in Noah Igbinoghene , Elijah Campbell and undrafted free agent Kader Kohou -- whom the team signed for $130,000 guaranteed and a $30,000 signing bonus. McDaniel did not express concern over the state of the position, instead offering support for the Dolphins' remaining cornerbacks. "I feel pretty good about the development we've had at that position," he said. "This is the nature of NFL football, and I would be a lot more concerned if I didn't really like the guys that are on our roster that really did some good stuff on Saturday." The Dolphins also placed fullback John Lovett on injured reserve and released punter Sterling Hofrichter , linebacker Deandre Johnson and safety Sheldrick Redwine .