He'd be a solid addition for this year, but he's a senior and I doubt he wants to wait another year to play, but I could be wrong.
I covered him for the last two seasons and tbh, he wasn't even the best corner on the team, Colby Burton was. But then Burton got hurt the first game of last season and Dunn took over as the top guy.
Dunn is really solid in man coverage, he had his bright spots against Tylan Wallace of Oklahoma State last year. Dunn was able to go step for step with him on some deep passes. Where he struggles however is coming forward. He did force a fumble against OSU, but he also got blocked too easily at times, which contributed to I think 2 Okie State touchdowns.
All in all, he's fast, he ran track at McNeese and I think won the indoor 60 meter hurdles title in the spring. I don't think it would be the worst pickup, Rumph could develop him into a solid FBS corner I think. However, I'd probably go after Brown and maybe hope another FBS corner hits the portal before going after him.