PHILADELPHIA -- It will go down in Philadelphia Eagles sports annals as one of many unanswerable questions and unsolved mysteries.

How good could Chip Kelly’s offense have been with both Jeremy Maclin and DeSean Jackson playing wide receiver at the same time?

The question was put to LeSean McCoy Wednesday. Before he remembered that Jackson is persona non grata inside the NovaCare Complex, McCoy’s eyes widened and he smiled.

“Just a lot of big plays,” McCoy said. “A lot of space, a lot of yards. That’s what I would think. But you never know.”

Those last four words were thrown in after McCoy stopped dreaming about what might have been and recalled that Jackson is he whose name shall not be uttered since his release from the team in March.

Kelly has explained that Jackson just didn’t fit what he wants from wide receivers in the Eagles’ scheme. He prefers bigger bodies and better blockers, which has been borne out in his apparent infatuation with Riley Cooper and the drafting of Jordan Matthews.

Asked Wednesday how Maclin, Cooper and Matthews have done in the wake of Jackson’s release, Kelly held his ground.

“If you look at our catches, those three receivers already have more catches, from what I've been told, than last year,” Kelly said. “I think our receiving corps has done a really good job -- all three of those guys.”

Last season, Jackson, Cooper and Jason Avant caught 167 passes in 16 games. In 14 games this year, Maclin, Cooper and Matthews have caught 182 passes.

Last season's trio amassed 2,614 yards and 19 touchdowns. This season's group has 2,403 yards and 18 touchdowns.

But that really answers the wrong question. Last season, the Eagles lost Maclin when he tore his ACL during training camp. Cooper moved up to the starting lineup and Avant was the veteran slot receiver. So they did well, but it was not the result of any kind of plan.

This season's group reflects Kelly’s preferences. He trusted Maclin to replace Jackson's production. Kelly also chose to give Cooper a new contract and draft Matthews.

Last season, Cooper caught 47 passes for 835 yards and eight touchdowns. This season, Cooper has 48 catches for 487 yards and one touchdown. The catches are similar, but the yardage and touchdowns are way down.

Matthews, who has 56 receptions for 709 yards and seven TDs, has more or less duplicated Cooper’s production from last season, with Cooper sliding down to Avant’s numbers.

But the real question is how the Eagles would have looked with Jackson and Maclin both on the field. How much strain would that have placed on opposing defenses? In the match-ups in which defenses were able to contain the Eagles’ passing game, would that extra bit of speed from Jackson have made a difference?

We’ll never know for sure.

This season in Washington, Jackson has 50 catches for 957 yards and five touchdowns. He has been limited by the team's revolving door at quarterback. On the other hand, Jackson has characteristically had extremely good days and fairly mediocre days. He leads the NFL with an average of 19.14 yards per reception. But he’s had three games where his total yards were below that average. Jackson has four games over 100 yards receiving and six games under 50 yards. He can be controlled by certain cornerbacks.

Would he have done better in Philadelphia? Probably. Jackson had career highs in catches (82), yards (1,332) and touchdowns (9, matching his best season). He did that with Cooper on the other side, just as Maclin has compiled his best numbers this season.

Would Maclin and Jackson both have put up similar numbers playing on the same field? No one can say, although McCoy’s smile spoke volumes.