New England Patriots Coach Bill Belichick, left, and Philadelphia Eagles Coach Chip Kelly are part of a new trend of up-tempo offenses in the NFL. (TIM SHAFFER/REUTERS)

Chip Kelly’s first play call in the NFL was traditional and unmemorable. Whether the Philadelphia Eagles’ first-year coach meant it this way, Chris Polk’s four-yard run up the middle on Friday was a nod to the game’s past — not the future that Kelly was supposed to usher in.

But when Polk was tackled, the race was on. Kelly began showing why he’s here. His next call was delivered quickly to quarterback Michael Vick, who relayed the assignment to the same offensive teammates who’d run the previous play — substitutions are so yesteryear — and with 16 seconds left on the play clock, snapped the ball. Another run, another quick call, and then another play.

On and on it went, the pace blazing, and after 2 minutes 15 seconds, Kelly’s first offensive possession became his first NFL touchdown.

“Honestly, it hurts your lungs,” Eagles tackle Lane Johnson said of his team’s tempo, after the New England Patriots’ 31-22 preseason win. “But when you see the defense is coming, and you know that they’re out of breath, you go for the throat.”

At the University of Oregon, this was the way Kelly built and ran offenses. He’s a strikeout pitcher: varying speeds and rhythms, and as soon as the defense relaxes, thinking it knows what’s coming, there is Vick’s deep touchdown pass, a heater high and tight.

“You can see the defensive player a little bit gassed, sucking for air,” center Jason Kelce said, “so you know you got them a little bit on their heels.”

This was a glimpse into why Kelly was so attractive for NFL teams after four seasons and 46 wins at Oregon. His fast-paced offensive scheme led the Ducks to promote him to head coach in 2009, to BCS bowls in each of his seasons in Eugene, and to making him the NFL’s hottest coaching prospect during the 2013 offseason.

“Every week is going to be slightly different,” Kelly said of his first season.

But is different good enough to chase a Super Bowl? More than that, is this the earliest stage of the NFL’s latest craze? In practices and in games, Kelly rarely uses substitutions. His offenses huddle only occasionally. If the play clock dips inside 10 seconds, something has gone wrong. And his teams can strike quickly: big points, fast players, defense more or less optional.

Kelly’s offense highlights an NFL trend — more plays with less time in between — and could, if all goes right, hold the keys to the next offensive fad. The hurry-up offense is nothing new, but 10 years ago, the Patriots led the league with 66.4 offensive snaps per game. On Friday, Kelly’s team ran 86 plays and gained 452 yards — impressive except that New England had 72 snaps, 442 yards and 31 points. This is the threat that Kelly offers — and the system that will define him.

But Kelly has faced obstacles. On Friday and throughout training camp, the Eagles have gotten in their own way. The point is to give Philadelphia more chances at big plays. But it also increases the chance of blunders; the Eagles fumbled three times Friday and occasionally looked confused against the Patriots, who started the speed-spread movement last season, averaging 74.3 plays and reaching the AFC championship game.

It was successful in New England, which had 92 offensive snaps in a December 2012 game, because Tom Brady is the league’s best quarterback. Without an elite passer, can Kelly lead a proper revolution?

When the league watches, deciding whether to copy the trend, coaches and executives will look first at the quarterbacks. After all, this is what these innovations are meant for: A way into the postseason for teams without one of the NFL’s best dozen passers. Kelly has a quarterback problem — Vick is 33 and injury prone, Nick Foles lacks mobility, and Matt Barkley is a rookie — so the spotlight will be on how teachable his offense can be.

“More and more teams are trying to go up-tempo, go no-huddle, put pressure on the defense, don’t let them make substitutions, don’t let them dial up all those blitzes,” said Rich Gannon, a former NFL quarterback who’s now a CBS game analyst. “But you’ve got to have a quarterback who can function in that system, in that world.”

If Kelly trains his starter to run his offense smoothly, other teams will flood their meeting rooms with Kelly’s philosophy. If the Eagles fail, outsiders will simply say the Patriots’ success last season was because of Brady. Among Friday’s early impressions: Foles losing a fumble on his first series and Barkley struggling early before finding a groove.

The other challenge will be fitting his pace into what the NFL will allow. Kelly said he met last week with officials to discuss tempo. This isn’t the Pacific-12; officials at this level reset the ball at their own pace, swap footballs when the clock stops and uphold the rule that, if the offense substitutes players, the defense will be granted time to set itself, too — which is one reason Kelly rarely sends in subs.

Kelly said he used Friday’s preseason game as a test of the offense he hopes to use, comparing his vision against the speed set by officials.

“We wanted to see if we could play with some tempo and get used to how they were spotting the ball,” he said. “I didn’t see any problems.”

Television networks also might have to adjust, accounting for more clock stoppages and changes of possession — another byproduct of cramming as many plays into 60 minutes — and longer games. On Friday in Philadelphia, the Eagles and Patriots each had 13 possessions and combined for 158 plays. Last year, all but three NFL teams — New England, Detroit and Indianapolis — averaged fewer than 70 offensive snaps. A year earlier, only New Orleans averaged at least 70 plays.

“I can tell you right away that the announcers aren’t going to like it,” Gannon said, “because it’s going to make them miss some plays.”

Extending games also means asking more of a defense, which is unlikely to do many favors for Kelly this season. Philadelphia allowed a 62-yard run on New England’s first play and later watched running back LaGarrette Blount — who played for Kelly at Oregon — run toward the sideline, reverse course, and then pull away from Eagles defenders for a 51-yard touchdown.

If the defense struggles as it did Friday — the Patriots gained 334 yards in the first half — that makes it even more important for Kelly to get it right on offense and put up the huge scores that made him famous at Oregon and brought him to Philadelphia.

“The mistakes you hope you don’t have, but it’s going to happen in the first game,” Kelly said Sunday, after reviewing footage from Friday’s loss.

For now, there is time — and Kelly has made a career out of doing more with time than most everyone else.