Glenn is the Def Coord for the Lions, and their defense is not ranked high, so how has Glenn proven himself? According to the link, they are 20th this year allowing 342 ypg. They were 19th in 2023, allowing 336 ypg, so they've slightly regressed.
https://www.foxsports.com/articles/nfl/2024-nfl-defense-rankings-team-pass-and-rush-stats