Hmm...some people on here are seeing a different I Johnson than I saw when he was playing.
The guy has the prototypical size NFL GMs and coaches love for a safety, but that's it. He doesn't have the range, takes bad angles, isn't a sure tackler, and doesn't read the game particularly well. Plus he's coming off an injury and a year away from the game. Maybe it's because he was playing for Groh and CAG's scheme made everyone look bad but that's what IJ has on tape right now. Maybe he improves several levels under Roof...I hope so.
Remember, he's being compared against other draft eligible safeties who also have the same size...but have better range, are better tacklers, reads the game better, and plays for DCs who put them in better position to make plays (this could change under Roof). There were 18 total safeties picked in the 2014 draft...that's SS and FS. So roughly 9 for each safety position.
http://www.nfl.com/draft/2014/tracker#dt-tabs:dt-by-position/dt-by-position-input:s
The question is, is IJ one of the top 15-20 safeties in the land?
http://www.cbssports.com/nfl/draft/prospectrankings/2015/FS
http://www.cbssports.com/nfl/draft/prospectrankings/2015/SS
CBS ranks him the #23 SS (or in the top 40ish for all safety positions) in the country for the 2015 draft...which puts him in the UDFA territory. Obviously draft stock can change depending on performance this season. But as of right now, it's tough to say he's a legit draft prospect. Remember, as good as Morgan Burnett was for us, and he was VERY good, he was a 3rd rounder.
Surprisingly, our highest rated prospect on the team is Shaq Mason rate as the #8 OG in the nation for 2015 (same source).
Those rankings really don't mean that much (if at all) so take it with a grain of salt...but still gives you an idea of what players for each position is out there.