"When we talk NFL free agency, we're almost always talking about unrestricted free agents, guys who have four-plus years of service time and whose contracts have expired. The bulk of offseason player movement in 2012 will involve UFAs.

But a rules tweak that resulted from last summer's NFL labor dispute could have ramifications for restricted free agents. (An RFA is a free agent with three seasons of service time whose contract is up.) In the past, if a squad wanted to sign another team's restricted free agent, the maximum compensation it had to give up was both a first- and a third-round draft pick. Under the new rules, now that team's maximum compensation is "only" a first-rounder. However, those same new rules now allow a team to place the franchise tag on RFAs, and of course, any team may still match any offer an RFA receives. Still, in the past when we generated lists of RFAs, it felt pretty nominal; it was highly unlikely for an RFA to change teams. Now, I'm not sure that's true. As a result, you're going to notice two very big-name RFAs on my list below. It's not inconceivable that they could sign elsewhere.

With that caveat, let's get to a list of the most important QBs, RBs, WRs and TEs who may be changing teams this spring and summer."