"I think they go hand in hand, but I think the ball needs to be able to travel from A to B with a certain velocity and pace," new Eagles quarterbacks coach Bill Musgrave said. "Most of the guys that get to this level, you kind of check that off right away."
But arms come in all shapes and sizes. Nick Foles doesn't have a cannon, but he has more than enough strength and the biggest arm of the Eagles' four quarterbacks. Michael Vick and Donovan McNabb held those crowns before Foles.
But as both those former Eagles quarterbacks proved, you don't necessarily have to have the strongest arm to be the best passer. Vick and McNabb could make throws Foles could only dream of making, but the combination of his quick thinking and reading of defenses, he said, has offset what he lacks in arm strength.
"I don't think you have to have an arm that can throw the ball 100 yards," Foles said Tuesday after the Eagles' first day of minicamp. "I think that you obviously have to be able to throw a football and be able to spin in all different climates. But it's really all about timing and understanding where to go with the ball."
Foles said he didn't know whether his arm had gotten any stronger since he entered the NFL two years ago. As a rookie, Foles had several throws that made it seem as if he lacked ideal power. His last pass that season was an underthrown toss to Jeremy Maclin against the Washington Redskins that fluttered and fell short.
But Foles had broken a bone in his hand earlier in that game. Still, there remained some doubt about his arm as he engaged in last year's competition with Vick. He tried to heave the ball out of the back of the end zone in a preseason game in Jacksonville but came up short and it was intercepted.
When Foles was thrust in after Vick was injured and finally took over at quarterback, there didn't seem to be many throws he couldn't complete, including the 20-yard out. Some suggested that Chip Kelly's offense didn't require a gunslinger, but the Eagles threw deep as often as any other team. However, a fair amount of his offense does necessitate quick-twitch decision making and a release to match.
"There's not one thing that we look for and say, 'You know, he has a quick release, but it's OK, he doesn't have a very strong arm,' " Kelly said. "I think you want the whole package in terms of what you're looking for."
The whole package should produce an accurate passer, though. Foles completed 64 percent of his passes in 2013, but there is room for improvement. He clearly has been the most precise of the quarterbacks this spring.
Mark Sanchez has been inconsistent. He will compete four on-the-bull's-eye passes in a row and then wildly toss a short pass 5 yards off target. Sanchez wasn't accurate with the New York Jets (with a 55.1 completion percentage), but he said September surgery to correct a shoulder injury that had been bothering him for three years should improve his throws.
"I feel like I have a pretty good arm. I feel like, if anything, it's stronger," Sanchez said. "It doesn't take as much effort to get it downfield."
The Eagles touted Matt Barkley's release after drafting him last year and then said that his recovery from a college shoulder injury affected his arm strength last season. But he hasn't looked any stronger so far this year, and there have been many incomplete passes.
If Barkley is to become a starter, he must have the timing and anticipation of Peyton Manning or Tom Brady. Because he doesn't have a pistol like Aaron Rodgers, Joe Flacco, Jay Cutler, Matt Stafford, or Colin Kaepernick, there is little margin for error.
Foles isn't in that class either, but he has had success because all of his other talents compensate for the lack of an elite arm.
"I think with confidence comes arm strength," Foles said, "and what I mean by that is I've been able to play the last couple of years, and you just develop the timing with the guys, you just understand the windows, so you know when it's a good time to throw a ball, and you can really let it rip."