I can understand Grimm to a certain extent, he was only a 1x Honorable Mention All-American selection in a program with scores of Consensus and Unanimous First Team All-Americans not retired.
The 3 offensive lineman who have their jerseys retired were all First Team All-Americans (Covert & Fralic multiple time/May only once, but won the Outland Trophy). Hell, Ruben Brown was a First Team All-American (Grimm wasn't), is in the College Football Hall of Fame (Grimm isn't) and had more Pro Bowl nods in the Pros (9 to 4). Grimm's profile is more in line with Stepnoski's (3rd round pick, multiple rings, multiple Pro Bowl/All Pros, All-Decade team, but Stepnoski was a Consensus First Team All-American (and a 3rd Team All-American the year before that).
Clancy is a little harder to figure. They put him in the same HOF class as two players with retired jerseys (Hennon & Lorri Johnson) and in the class before another Jersey Retiree (B. Knight). Makes *no* sense.