The recent progress is because of one of two things. 1) The Bills beefed up their offer to Johnson. 2) Stevie's agent found out in Indianapolis there wasn't as much (monetarily speaking) interest on the open market. Whatever the case may be, a deal is closer than it has been leading up to this point.
Why is this relevant? As we pointed out a few weeks ago, over the past two seasons Jackson and Johnson have had similar production. In fact, Johnson has probably been better and more consistent. Considering that they're the same age, it stands to reason that the contracts they sign this offseason will end up being similar.
Jackson has been franchised tagged, so he's going anywhere, but both he and the Eagles have expressed interest in continuing to work on a long term deal. If Johnson and the Bills can come to an agreement in the 10 days, that would certainly help set a guideline for a DeSean deal.