If my premise is wrong, then this post is valueless. But if right, it's a factor.
Premise: an offseason negotiation with Wilson renegotiates the last year of his 4 year rookie contract.
Option 1 for Wilson is to play out 2015 at $750k THEN hit the free market or renegotiate with Seattle. Under those circumstances, he'll be looking at more per-year money in his new contract (let's say Flacco money of 6 years, $120 mil) than if he opts for...
Option 2: Wilson renegotiates the last year of his rookie contract, which gives him a whole lot of new money (mostly in the signing bonus) in 2015 than he's currently going to make, but less than the per-year amount if he were negotiating as a free agent.
The conclusion here is that a new Wilson contract worth Joe Flacco money - 6 years at $120 mil, is not an underpay for Russell. Flacco was a free agent. Wilson is not. By tearing up his $750k contract for 2015 and replacing it with 6 years at $120 mil, it's basically the same as a 5 year $120 mil contract on the open market (after a year at $750k), or about $24 mil per year. Sounds fair and reasonable to all parties to me.