Riley Cooper is not a burner. That’s putting it mildly.

Cooper ran 4.53 at the 2010 NFL scouting combine, which ranked him 21st out of 35 wide receivers who ran the 40-yard dash that February day at Lucas Oil Stadium in Indianapolis.

That helps explain why despite terrific hands and very good size -- Cooper stands 6-foot-3, 222 pounds -- Cooper wasn’t drafted until the middle of the fifth round, when the Eagles took him with the 159th pick.

Cooper was the 19th wide receiver taken in the 2010 draft, and the 4.53 is one of the main reasons.

For a linebacker, that’s fast.

For a receiver, it’s slow.

In fact, since 1999 -- the span of 15 drafts -- Cooper’s 4.53 ranks in the 31st percentile among all wide receivers who ran the 40 at the combine.

According to data collected by NFL Combine Results, Cooper’s 4.53 was tied for 312th out of 450 wide receivers that ran the 40 from 1999 through 2013.

So, with all that said, here’s the reality:

Fourteen weeks into the 2013 season, Cooper leads the NFC with 19.3 yards per catch and ranks second only to Josh Gordon in the entire NFL in yards per reception. The explosive Gordon is averaging 19.7 for the Browns.

Cooper is also fifth in the NFL with six receptions of 40 yards or more, just two fewer than Gordon and one fewer than DeSean Jackson.

Cooper can’t run like Calvin Johnson, Mike Wallace or Santana Moss, who all were timed in 4.35 seconds or better at the combine, but he’s somehow got a higher average and more long receptions than any of them.

All of which proves one thing: Speed isn’t the only factor when it comes to making big plays.

It may not even be the biggest factor.

“Speed isn't the [biggest] factor, because if it was, then the fastest guy in the NFL would catch the most deep balls,” head coach Chip Kelly said. “It's not that. There's a lot more to it.

“This isn't a track meet. It's who has the ability. ... There's a lot of fast guys that run down the field, but when the ball is not thrown directly to them, they can't adjust to it. They are straight‑line guys that can't veer off course.