Allen at his best is a great center but there's a lot of advantages if Shelton wins the starting job (we have him locked up for two years, he's bigger, there's position flex with him, Allen's spot can be replaced with a rookie center on the practice squad). In that scenario, Allen is cut, btw.
I'm pulling for Shelton to win the starting job but Allen being healthy and getting back to his 2021 performance would be a great consolation prize!