The NFL's free-agent signing period will open Thursday, at which point the Bills are expected to sign fullback Patrick DiMarco, sources told ESPN on Wednesday.

Here is more on the move:

Terms: Four years, $8.5 million with more than $4 million guaranteed (per ESPN NFL Insider Adam Caplan)

ESPN 150 ranking: No. 49

Grade B-plus: It's hard to feel strongly one way or another about a team signing a fullback. In this case, the Bills are swapping Jerome Felton for DiMarco, who ranked one spot below Ravens fullback Kyle Juszczyk on ESPN's top 150 free-agent rankings. ESPN NFL Insider Adam Schefter reported earlier Wednesday that the Bills were "favorites" to sign Juszczyk, but adding DiMarco presumably takes them out of the running. Both Juszczyk and DiMarco have made the Pro Bowl over the past two seasons.

What it means: The change in offensive coordinator from Greg Roman/Anthony Lynn last season to Rick Dennison this season likely triggered the change in style of fullback the Bills wanted. Felton was a bruising lead blocker who rarely offered much as a receiver or runner. DiMarco has only one career carry but has caught 20 passes over the past two seasons for 162 yards and three touchdowns. That adds an extra element to an offense that will again be headlined by running back LeSean McCoy and wide receiver Sammy Watkins.

What’s the risk? The Bills are likely getting DiMarco for a smaller price than Juszczyk would have commanded, so the financial risk is reduced. It remains to be seen how the deal will be structured, but the average of just more than $2 million per season is likely to eat further into the Bills' already limited cap space of about $21 million. Restructuring Tyrod Taylor's contract likely freed up some cap space, but the Bills have needs at wide receiver, right tackle, linebacker and cornerback that must be addressed; fullback was not as pressing of a priority.