As 35+ yos, DW can sign Jumbo and Patty to "bonus" contracts (IOW, doesn't have to count against cap), or to minimal ($1-2m each) deals (as I don't think it's about the $$).
The thing is, you don't really want to "go to the cap" on a 23 man roster, when there are possibilities of trades in season where you might take on (a bit) more salary.
My guess is that Thornton and Marleau will take the lesser salary to help with the team this season, for possible acquisitions for stretch push and playoffs.