I'll go first ... Linemen linemen linemen.
Both offensive and defensive current schemes (which are very popular around the NFL right now, and good chance we might get someday again, even if coaches are switched) put more pressure on the linemen.
Right now, the OL lacks talent as a lot of the OL have not lived up to their draft status, and it appears (to me) Gute is not good at selecting OL.
DL, is alright in talent, BUT they can't seem to handle the additional pressure of the scheme helping the DBs and leaving them more on an island up front. And against better OLs (which we don't play that many of the best OL this year), against the better OL, they either need to get out of the scheme or additional dominant player.
Also, the defense scheme needs S and slot CB... improvement, to help the middle of the field.
And the offense needs more TEs/FBs as the scheme is based on versatility of having multiple mid-sized bodies that can do multiple things. Right now, we just got Musgrave. Though Sims is showing some potential, and three of them are rookies with possible potential to grow... but... Gute's draft history with TEs and 3rd round picks isn't pretty either.
But mostly linemen.