This post is late because of internet issues but...
Myles Jack and Jalen Ramsey were my top two options for the Jacksonville Jaguars since free agency ended. Adding both of them to the defense makes the defense more athletic, more physical, more versatile, and just more talented then it has been in a long time.
I am not sure where Jack is going to play at first but the thing is, it doesn't really matter. Whatever role he is used in is likely one that he is the best player on the roster for and one that he can excel at. There is no other player on the team with the blend of his size, speed, and coverage ability.
Bradley has mentioned he can play both MIKE and WILL and I could see them use him as an OTTO or a strong safety as well. Even blitzing him off the edge. There is nothing he can not do in the front seven.
As for injury risk, I wouldn't worry about it until there is truly something to worry about. For now he is okay and could play ball. That is worth the investment of a second and fifth round pick.
Myles Jack is a Jaguar. That is what is worth focusing on right now... not some hypothetical injury concerns that may never truly be worn concerning over.