Grimm did a very solid job of filling in for Mike Stonebreaker in 1989, and ended up playing a lot in 1990.
A large majority of people were clamoring for Demetrius Dubose to be put in as the starter during his sophomore year. While it was certainly true that Dubose ran the 40 about a half second faster than Grimm (Dubose was hand timed at 4.51), and was certainly stronger and more athletic, he had a bad tendency in 1989 and 1990 to over-pursue his tackling targets, not to mention, still learning how to cover the medium range routes.
If anything, in 1990, there were plenty of times that he took bad tackling angles against "Touchdown" Tommy Vardell that led to several large gains in that 36-31 loss.
That left Lou no choice but to use Donn Grimm for a lot of that season, and to his credit, Donn Grimm still turned in a good season, coming up some clutch plays.
It was around the Miami game of 1990, that Dubose became a better player, and improved throughout 1991, and in 1992 that he truly became the powerful force we had wanted him to be earlier.
Rest in peace, Demo.