He may be lightweight but is he as explosive as shazier? This is a thing people like to say but shazier was FREAKISHLY explosive, he was the most explosive LB in the league and would probably outrun most SSs in 20 yard sprints. They replaced shazier with mark barron and I would never consider Barron a capable replacement because he’s not nearly as explosive.
I’m not sure Simmons is built like that, he might be closer to a Derwin James, plenty of athleticism but more physical than explosive, physical enough to play ILB in the nfl though? Doubt it, explosive enough to make it a worthwhile position change? Maybe, but I would have zero doubts about his ability to play safety.