We don't have 4-5 top guys. We have Sean Lee. Jaylon hasn't earned 'top guy' status.
And you need 4-5 LBs who can actually play in this league if you're going to make it through a full season plus playoffs. Especially when your best LB has a long history of soft tissue issues. You can get away with having 2 of those guys be quality developmental players, but you need three guys minimum who can all start and play will for you across the WIL and the MIKE or in coverage packages.
LBs are your core special teams players, too, so it's not like it hurts to have an extra one lying around. We're losing Durant and Wilber this year, as well, so those spots need to be replaced. It's not like we have some embarrassment of riches at the LB position on this team. It's killed us for years, now, and I have no interest in seeing it kill us one more time in 2018.
Fix the S problem. Fix the LB problem. Keep the pressure players. Stop complaining about why it is we can't cover well enough to beat good QBs. It's pretty simple.