It is in early summer, as coaches and players are working toward the rapidly approaching season, when NFL roster-builders shift their gaze a bit further. Preliminary work on the 2015 draft is underway, as is large-scale planning for a class of veteran free agents that carries some major names at the receiver position.

Colleagues Mike Sando and Bill Williamson evaluated the class this week, especially as it relates to the San Francisco 49ers' dilemma with Michael Crabtree. My role in this little project is to be a Debbie Downer of sorts and question how many of these playmakers -- if any -- will reach the free-agent market next spring. At the moment, there are more reasons to suspect a majority will remain with their current franchises.

As we discussed in March, the NFL marketplace rarely prompts top players in their prime to change teams. They are lured by big offers in the months, or sometimes years, before the expiration of their contracts, and exceptions -- such as Peyton Manning's shift to the Denver Broncos in 2012 -- are usually dictated by unique circumstances. While the 2014 uptick in salary-cap space provides more room for free-agent maneuvering, it also offers the same flexibility to re-sign players before the market opens.

Meanwhile, second contracts are typically sound investments for a receiver. The bar graph at the top of this post shows that they maintain close to peak production between the ages of 27 to 31. (The data is based on production for all receivers who have played at least four NFL seasons since 2001, with a minimum average of 50 receptions per year.) That pattern differs notably from, say, running backs, whose production declines after the age of about 27.

As the chart to your right illustrates, eight of arguably the 10 best pending free-agent receivers will fall into that age slot -- or younger -- during the 2015 offseason. Their future will depend in part on factors we can't project, including injuries and the potential for front-office change, but it's difficult to look at this list and pick out an obvious instance where a player seems set to move on.

The Green Bay Packers have allowed two 30ish receivers, Greg Jennings and James Jones, to sign elsewhere in successive years. But Jordy Nelson, who will be 30 when the 2015 season begins, has spoken adamantly in recent days about remaining with the Packers -- and does not appear concerned about losing leverage in saying so.

For the most part, this list is stocked with young receivers in their prime. Why would the Dallas Cowboys feel compelled to part ways with Dez Bryant? (Wait, don't answer that.) The Packers couldn't possibly be thinking of letting Randall Cobb go, could they? Torrey Smith seems a natural fit for the Baltimore Ravens as long as deep-throwing Joe Flacco is the quarterback.

The biggest question among this subgroup could be Crabtree, who has produced only one 1,000-yard season in his five-year career. The 49ers have a talented roster and a relatively tight salary-cap situation, and Crabtree might push toward the open market while assuming most of his classmates re-sign with their current teams.

Otherwise, the guess is that this potentially star-studded class will be whittled down considerably before the 2015 market opens. It makes too much sense.