What positions can be left un-drafted
Defensive tackle is a need primarily because Duane Brown cannot keep going forever and becomes more likely to pick up injuries with every passing season, also Brandon Shell is in entering the final year of his contract.
The Seahawks may choose to seek a bridge replacement via free agency or trade rather than the draft as this is a pretty weak DT class in the draft.
I also feel that cornerback is best addressed outside of the draft as the five best players at this position will have gone before the Seahawks first pick. This is also when the real quality ready to play from day one options will have gone.
Even if the Aldon Smith situation works out badly for him and the Seahawks, there is plenty of depth at the DE position, so given the lack of available picks, this may well be dropped down the priority list.
Similarly at safety, where Jamal Adams, Quandre Diggs, Marquise Blair and Damarious Randall may be viewed as enough to satisfy the need for 2021.
Guard is a position that could do with some more depth adding to it, but drafting a center may actually open up the possibility of using Ethan Pocic as cover at both at center and guard, which he played some of at LSU before converting to be a center.
From my analysis of problem areas for the Seahawks in earlier pieces, I have identified the red zone production from the ground game, or lack of it to be precise, as a major concern. We all saw how later in the 2020 season, teams just sought to move away from the passing game in the red zone, and the Seahawks lacked the ability to make them pay on the ground.
So I think trying to tackle this via the draft should be the second priority for the Seahawks.