Here is a list of position with unproven players or busts at the position:
RDE, DT, MLB, OLB, SS, FS, All 3 corner spots. The ONLY guys that have proven themselves to be good on defense are Lee, Lawrence, Irvin. Everyone else has question marks.
I've got hopes for some of those spots, but overall, I think it's fair to say a lot of players have a lot to prove on defense. After 2016, there was a lot of praise for Anthony Brown, but he took a clear step back last season. Awuzie and Lewis could do that. Jones could prove ineffective at corner. The safeties certainly have a lot to prove. Vander Esch could bust. Jaylon could be no more than what we saw last season. There are definitely questions at tackle outside of Irving, and he and Lawrence could even go south (although I feel pretty confident about them.) This team will be in trouble if it has to depend on Lee staying healthy in order to have a decent run defense.
However, the reason for hope is that their is a lot of potential with this group. We're not having to rely as much on the George Selvies and Benson Mayowas of the league to be starters. Yes, we're checking out what players like Ealy and Ward might can be, but there is young talent that they'll have to be better than to earn a starting spot. There's a good possibility that every starter on this defense this year will be home-grown. (I know Irving's not homegrown, but he's pretty close.) Thomas at LB, Price at DT, Ealy and Jones at DE/DT are the only players we've got who spent significant time with other teams. Of course, that won't matter if the homegrown talent fails to produce.
