I guess if I graded the offense - it would go this way - I'd be happy to start any season with these blessings - so in response to the OP, I think we're basically done with the upgrades.
QB: Starter A, Backup B - Russell Wilson - amazing first year, no reason to suspect a drop off, Flynn is a capable backup and I feel very good about it. QB3 - not relevant for this dialogue
RB: Starter A, Backup B- Lynch has had minor injuries the past two years, but has played through it. Without Washington, you lose a lot of football IQ and experience. Turbin is a capable backup. RB3 might be a nice add
WR: Starters B, Depth B - Like that Rice stayed healthy last year, but still plays in a way that gives me fear about his durability. Harvin, again not much in the way of full seasons - but so versatile and love that testimonial from AP's Twitter post. Tate, Baldwin - nice pieces. Might need a WR5 in the draft or is Kearse the guy?
TE: Starter A-, Depth B - I really like what we have here. Perhaps one more for depth - interested to see what Fells has. I really love McCoy - great swagger and explosive.
OL: Starters B, Depth B- - Would love to say everything is locked up - but like the overall depth due to the ZBS - some players are exceeding expectations while stars are shining (Okung, Unger). A lot of guys played meaningful downs last year - love that.
The amazing part about the offense is its interchangeable parts and flexibility of formations. The read-option gave even more life to the running game last season - so with the addition of Harvin, I expect that trend to continue. This is a team that scored among the leaders in the 2nd half. I don't expect that to change. As a matter of fact, I think this team might score more than any other Seahawk team.