"Pretty much it's just reps," Sproles said, when asked how a running back makes himself into a receiving threat who can move outside if needed. "The more you do it, the more coverages you see, then you start knowing stuff."
"We used to work on it in the summertime," when Saints quarterback Drew Brees would gather his top weapons in San Diego, Sproles said.
Sproles, who turns 31 next month, has more catches than carries in three of the last four seasons. He is the Eagles' top offensive offseason addition; he could be the player most counted on to take the place of DeSean Jackson as a weapon defenses must game plan against.
Not that Sproles necessarily sees it that way.
"We're two different players, two different positions," said Sproles, who speaks deliberately, choosing words carefully, having battled a stuttering problem since childhood. "So, I can't [replace Jackson]." He said Jackson "has that track speed."
Indeed, Sproles ran a 4.47 40 at the 2005 NFL Scouting Combine, on his way from Kansas State to becoming a fourth-round selection of the Chargers, while Jackson ran a 4.35 out of Cal, headed to the Eagles in 2008, and there definitely is a huge difference in Sproles' career average of 8.9 yards per catch and Jackson's 17.2. (Note: an earlier version of this story included an incorrect 40 time for Sproles.)
It's been noted that Sproles' totals from scrimmage for the Saints last season - 220 rushing yards on 53 carries, 604 receiving yards on 71 catches - weren't close to what he put up in 2011 (87 carries for 603 yards, 86 catches for 710 yards). The history of over-30 running backs is not encouraging.
Sproles said yesterday that when he looks at himself on film these days, he sees the same guy who set those career highs. It isn't clear whether NFL personnel people see that, as well. The Buffalo Bills' website recently noted that Bills running back Fred Jackson, now 33, last season became just the 10th back in NFL history to run for more than 800 yards and catch passes for more than 300 after age 31.
But though Sproles said yesterday he hasn't been told anything about his role with the Eagles, everyone assumes a limited workload - maybe six or eight touches a game from scrimmage. It seems reasonable to expect a 31-year-old to be productive used that way.
At the NFL meetings, when Kelly spoke with reporters about the addition of Sproles, he seemed to feel Sproles would make it harder for opponents to play the man-press coverage the Eagles struggled against in 2013.
"The addition of Sproles, are you gonna play us in man?" Kelly asked then. "Now you have to have a linebacker cover him if he's the back. That's kind of a huge addition, when we thought about bringing him in."
Kelly said then he wouldn't know exactly how he wanted to use Sproles until he saw him in action. That's what he's seeing now, and Kelly is scheduled to speak with reporters today, so expect an update.
Sproles said he hasn't worked in the slot yet, as the Eagles continue organized team activities that were driven into the indoor facility yesterday by rain, but "they say it's coming."
He feels he's picking up Kelly's offense quickly, he said, but the toughest stuff isn't in the playbook.
"This is really not that complex. The main thing is the tempo," Sproles said. "Once you [finish] a play, you've got to hurry and get back to the line. Then pretty much it's finding the guy who's signaling [from the sideline]."
Sproles sees similarities between Kelly and Payton - both "fun coaches, players' coaches," he said - but he said in his two previous stops he's seen nothing like the Eagles' approach to sports science.
"When you come in [to the training room], they already know where you're sore," he said. "When you go in the weight room, you're not doing the same lifts everybody else is doing, you're doing [a specialized routine]. I like that."
Sproles said he doesn't know yet if he'll return kicks for the Eagles. His 37-yard kickoff return against them in January's wild-card-round playoff game was a pivotal play, especially after Eagles corner Cary Williams had to take Sproles down with a horse-collar tackle to keep him from scoring. After the 15-yard penalty, the Saints were able to easily move in for a chip-shot field goal on the final play of their 26-24 victory.
"The return was supposed to go left, but when I saw [a defender from the right side] cross my face, I was like, 'Man, let me just try to make something happen.' I just took off to the right," Sproles said.
Sproles said since joining the Eagles, he has had a chance to discuss the play with Williams.
"He said he was sorry about it, he didn't mean to" do anything dangerous, Sproles said. "He said, 'I had to do something.' "
Of course, if Sproles had taken the Eagles' offer in 2011, instead of signing a 4-year, $14 million deal from the Saints, he and Williams might have been teammates for that January game.
Sproles said when he left San Diego, the Eagles and the Saints were the finalists.
"It was close," he said, and then repeated, "it was close."
Why did New Orleans come out ahead?
"I don't know," he said. "That's just the way it fell at the time."
On Twitter: @LesBowen