THE EVALUATION of NFL free agents is similar to the evaluation of major league prospects in that a certain time of year rolls around and suddenly people are awash in opinions about players that they've never seen play on a regular basis.

You need only look back a couple of offseasons to find a glaring example of this phenomenon. One month, you're counting Lombardi trophies while breathlessly watching a news helicopter follow DeMarco Murray to his first day of work. The next month, you're watching DeMarco Murray play and thinking, "Wait, this is DeMarco Murray?"

The lesson of Murray and Byron Maxwell and a substantial majority of the free agents the Eagles have signed since their last playoff win is that there is often a huge difference between a player's ability to impact a fantasy football team and his ability to impact a real one.

It's a notion that gained some premature pertinence around these parts with Thursday's news that the Eagles had declined their opportunity to add former first-round draft pick Michael Floyd to their much-maligned receiver corps after the Cardinals released him in the wake of his DUI arrest in Arizona. Rather than spending the $1.3 million in salary-cap space that claiming Floyd would have required - money that could otherwise be rolled over into 2017 and thus spent improving a team that isn't already eliminated from playoff contention (in principle, if not mathematically) - the Eagles allowed Floyd to pass by them on the waiver wire, where he was eventually claimed by the Patriots.

Forget the fact that passing on Floyd was almost self-evidentially the right move (even if the Eagles love Floyd, they're better off tacking $1.3 million onto their best offer this offseason, when he will become a free agent, than wasting that money on three meaningless weeks of his services). The more interesting thing to note was the real-time reactions of Eagles and Cardinals fans as they followed the developments of Floyd's arrest, release, and rebirth. Folks in Philadelphia saw a former first-round draft pick with all of the measurables a team could want and averages of 55 catches, 910 yards and six touchdowns from 2013 to '15. And the Cardinals, where the range of emotions started with good riddance and topped out with ambivalence, most conveyed with video clips of Floyd dropping the kind of routine balls that have Eagles fans counting down the days remaining on Nelson Agholor's contract.

None of this should be mistaken for a suggestion that the Cardinals' fan base is correct in its assessment of Floyd, or that the Eagles' fan base was incorrect in its assessment that Howie Roseman and Doug Pederson had nothing to lose by putting in a waiver claim on the former Notre Dame standout, or that the Patriots were correct in their assessment that adding Floyd was worth the hit to their future payroll flexibility. Maybe $1.3 million will prove to be a smart price to pay for the exclusive negotiating rights that the Patriots will now enjoy with Floyd between now and the start of the 2017 free-agent signing period. Maybe it will prove to be a price the Eagles would have been wise to pay. The point, in part, is that it is difficult for one person to form an educated opinion on the validity of adding a player if that person has not studied all of that player's snaps with an eye toward the role he'd be asked to play in a given scheme. Hence, the entire departments that NFL teams dedicate to such matters. And even then . . .

Another part of that point is that fixing the Eagles is not as easy as Howie Roseman flipping open his copy of Street & Smith's Guide to Giving a Franchise Quarterback Some Help.

One of the better moves of this past offseason was the Lions' signing of former Bengals receiver Marvin Jones, who enters Week 15 with 46 catches, 797 yards and four touchdowns (that's an average of 17.3 yards per catch). From 2013 to '15, Jones averaged 58 catches, 764 yards and seven touchdowns, missing one season due to an injury. He signed a contract that will cost an average of $7.5 million against the cap over the first three years of the deal.

Eric Decker was a smart sign for the Jets post-2013, at least two seasons, averaging 77 catches for 994 yards and eight touchdowns in his first two years after signing with the Jets for an average cap number of $6.15 million over the first three years. Golden Tate gave the Lions some value at an average cap number of $5 million over the first four years of the deal he signed that offseason. DeSean Jackson was dynamite in his first year post-Eagles, but over the last two has reminded us why Chip Kelly was willing to move on, with 72 catches, 1,274 yards and eight touchdowns in 22 games in 2015-16. Certainly, he is a weapon when healthy, but at an average $7.1 million cap number per year.

To put that in perspective, the Eagles will enter the offseason with roughly $160 million committed toward the 2017 cap, per figures compiled by OverTheCap.com, leaving them roughly $5 million wiggle room under a hypothetical cap of $165 million. They could add another $7.75 million by releasing Connor Barwin, $4 million by releasing Ryan Mathews, $4 million by trading or releasing Darren Sproles, $3.2 million by releasing Leodis McKelvin. But those players need to be replaced, and after that you might be looking at no more than $15 million in wiggle room.

The reality of the Eagles' situation is that they might have to settle for incremental improvement at wide receiver while perhaps making their big move at cornerback (a position that includes the Rams' Trumaine Johnson and the Bills' Stephon Gilmore, with a deep draft class to boot), or on the defensive line (who offers more bang for your buck: a wide receiver, or Bennie Logan?). The Eagles' reality is they might find more wisdom in the lower reaches of the receiver market. Think Pierre Garcon instead of Jackson, Kamar Aiken instead of Terrelle Pryor, Brian Quick instead of Floyd.

The lesson of the Eagles' inaction on Floyd just might be: Get used to it, you'll thank us later.

@ByDavidMurphy