Under his previous deal, Jackson would have hit the open market next March shortly after he turned 34. The market for a running back that age would be very limited, and frankly it would be shocking if Jackson left Buffalo after nine seasons.
In other words, the Bills could have waited until after the season to negotiate with Jackson and would not have risked an increase in his value, even with a good season.
That reality is reflected in Jackson's extension. There is no guaranteed money in the deal, so the team avoided any risk in electing to sign Jackson now. In a sense, it's a symbolic extension.
Here is the breakdown of his contract:
Base salary: $2.35 million
Roster bonus: $150,000 (paid in $9,375 installments per game active)
Workout bonus: $100,000
The $2.35 million base salary doesn't become guaranteed until after Week 1 of the 2015 season. In the event that Jackson's play declines this season to a point where the Bills either need to cut him or he retires before Week 1, the Bills are only on the hook for the $100,000 workout bonus.
Overall, Jackson's cap number will drop from $3.85 million this season to $2.6 million if he is active for the entire 2015 season. Until Jackson proves otherwise, he's worth that money.
But the structure of his deal is a reminder of the tricky nature of franchise icons in the latter stages of their careers. Contracts should not be rewards for past performance; they are agreements about future performance and pay.
Other than putting pen to paper and holding a news conference, there isn't much else to this deal. Jackson doesn't gain any security and the Bills stay on a year-to-year basis with him, as they should.