The argument is simple and largely true: Because of his speed and elusiveness, Jackson stretched opposing defenses like warm taffy. They had to account for him at all times, and his presence opened up opportunities for his teammates: LeSean McCoy, Riley Cooper, the tight ends, et al.
None of what follows is intended to diminish Jackson's talent or the elements that he brought to the Eagles offense. But it's worth noting that during the years 1999 to 2012 A.D/B.C. (Andy Domini, Before Chip), the Eagles offense probably needed a wide receiver with Jackson's skills more than it does now.
Andy Reid was a pass-first coach. Always was, always will be. And what were the two primary frustrations with Reid over his first several years as Eagles head coach?
One, that it took him until 2004 to recognize that, if the Eagles were going to throw the football as often as Reid wanted them to, they needed better starting wide receivers than Charles Johnson, Torrance Small, James Thrash, and Todd Pinkston.
Two, that once the Eagles acquired a bona fide No. 1 wideout, they didn't do more to accommodate the demands and placate the idiosyncratic personality of Terrell Eldorado Owens.
The Eagles said goodbye to Owens then, and they said goodbye to Jackson now, and hence, the freakout. The connection between Owens' and Jackson's exits is easy enough to make, but only if you overlook how different the Eagles offense was under Kelly from what it had been under Reid.
Last season, the Eagles attempted 508 passes and 500 rushes - a 50.3/49.7 percentage split that, once Donovan McNabb had established himself as the starting quarterback, would have been unheard of during Reid's tenure. Just five teams had higher run-pass ratios in 2013. Two of them, the New York Jets and Buffalo Bills, started rookie quarterbacks. The others were the three best teams in the NFC: the Seattle Seahawks, the San Francisco 49ers, and the Carolina Panthers.
That statistic comes with the requisite disclaimers: A team with a lead tends to run the ball more frequently, and each of those three clubs had an elite defense, which the Eagles, at the moment, do not have. But it's interesting that the two most accomplished wide receivers among the Seahawks, 49ers, and Panthers were Anquan Boldin - who is 33, 6-foot-1, and 220 pounds, and not among the league's fastest players - and Steve Smith, whom the Panthers allowed to sign with the Baltimore Ravens last month.
So the notion that the Eagles must "replace" Jackson with a similar receiver doesn't necessarily hold water. They are likely to draft a wide receiver to accompany Cooper and Jeremy Maclin - one who could be slower than Jackson but bigger and stronger, closer to Boldin's template - and considering that tight end Zach Ertz and tackle Lane Johnson were starters as rookies, it's not outlandish to think a first-year wideout could make an immediate contribution in Kelly's offense.
They will have Ertz, Brent Celek, and James Casey at tight end. They will have McCoy and Darren Sproles in the backfield, both of whom are excellent pass-catchers. They are not lacking for weapons.
The obvious difficulty in comparing the Eagles to those three top NFC teams is at the quarterback position. Nick Foles isn't nearly as mobile as Russell Wilson, Colin Kaepernick, or Cam Newton. With their legs, those three can lend their offenses a dynamism that Foles can't to the Eagles'.
So what will all this mean for the offense this season? It could mean an increased emphasis on the run and a more creative use of those tight ends. It could mean fewer big plays but better ball control. No matter how the system looks, no matter how it operates, this much is certain: Chip Kelly doesn't appear inclined to second-guess himself about letting his best wide receiver walk away.