So when Kelly has to make a choice in the Eagles' ballyhooed quarterback competition, which kicks into full gear next week when training camp commences, it would be a good bet to assume he will select the most precise passer.
Michael Vick, in 10 NFL seasons, has never been among the league's most accurate quarterbacks. But his numbers have improved since he came to the Eagles four years ago. Nick Foles completed nearly 70 percent of his attempts as a senior at Arizona and hit on a respectable 60.8 percent of his throws as a rookie last season.
Matt Barkley left Southern Cal as one of the storied program's most efficient passers, but the jury is still out on how his game will transfer to the NFL. Dennis Dixon has thrown only 59 passes in the NFL, but he set the bar for accuracy at Oregon when Kelly became offensive coordinator in 2007.
Each quarterback at this point in his career - Vick more so than the others - has established his throwing mechanics. Kelly said last month that he can assess why a quarterback is inaccurate. But at this stage there is only so much improving that can be done.
"You can see that, but a lot of times by the time they get to this level that's the way they do it," Kelly said as he prepared for his first camp with the Eagles. "You're not going to be able to change it because they've thrown it that way for thousands and thousands of hours of throwing the ball."
But could Kelly's offense improve a quarterback's accuracy, and in this instance, be better for one passer over the others? It's difficult to say at this point. Foles appeared to be the most accurate in the sample of practices the media were permitted to attend during spring workouts.
The players weren't wearing pads, though, and the defense was restricted in what it could do. There should be some separation at training camp, but it will likely take preseason games to properly evaluate the quarterbacks.
"We've been out there in shorts and T-shirts since April 1. And I'm going to name a starting quarterback out of that?" Kelly said. "They haven't been hit. There's been no rush. I don't think it's fair."
There is a lot that goes into being an accurate passer, but "first and foremost," Kelly said, "it starts with their eyes."
"Where are they throwing the ball? Because the eyes lead the body," Kelly continued. "And then a lot of the accuracy issues that occur with anybody throwing the football goes to footwork. Is your body lined up with your target in terms of where you're trying to place the ball?"
When Vick was at his best in 2010, completing 62.8 percent of his passes, his mechanics were sharp. When he set his feet and was square, the throws were on target. But in the last two seasons, for whatever reason, Vick's mechanics have been erratic.
The decline really started at the end of the 2010 season, but in 2011-12, Vick completed only 59 percent of his throws, still considerably better than his numbers in Atlanta (53.8 percent).
There were several other factors that contributed to his decline - the general malaise of the offense, dropped passes, inconsistent blocking - but Vick has said that he developed a few bad habits in the throwing department.
"There's a confidence level there that's outstanding, but he's humble," Eagles offensive coordinator Pat Shurmur said. "He's the first one to admit he's made a mistake, which is part of the learning process. That's why, I think, Michael can get better at everything he does."
He's 33, so that remains to be seen.
Foles doesn't have Vick's arm strength, and thus less margin for error, but he was very accurate in college (66.9 percent) and showed that he could throw the ball on time in seven games last season. He also made his share of errant throws.
But Kelly's new offense gives Foles, like the others, a fresh start. And understanding the scheme, the timing of the throws, and properly going through the progressions are factors that can improve a quarterback's accuracy.
"It's a day-to-day thing, but in my mind I try to simplify it," Foles said. "When we first got the playbook, you get a play and I was like, 'All right, this is similar to a play I had last year or a play I had in college.' So I try to go back in my history of when I used to rep the play, and when I go out there I just play."
Barkley, who completed 64.1 percent of his passes in college, said that accuracy and decision-making go hand-in-hand, especially in Kelly's up-tempo offense.
"There's so many different ways a play can go, depending on the defense, depending on the route runner, depending on leverage and whatnot," Barkley said. "So being able to process all the possible decisions you could make and be able to make the one in a matter of a second, that's important. That's what they're looking for."
The throws not only have to be completed but "the football has to be where the receiver can do the most with it so that the play just doesn't end with the receiver catching the football," Shurmur said.
At Oregon, Kelly placed a premium on yards after the catch because of the great number of short passes in his spread offense. Last season, Ducks quarterback Marcus Mariota completed 68.5 percent of his throws.
The redshirt freshman, who was a 64 percent passer as a high school senior, beat out a sophomore for the job. Kelly and his offense certainly helped Mariota's accuracy, but as the coach has said about the Eagles' competition, the cream will rise.
"There's two ways to get better, and that's either elite selection or elite training," Kelly said. "But it's a lot easier to train somebody that has the ability to do it than to say, 'Hey, we can teach him.' "
Contact Jeff McLane at firstname.lastname@example.org. Follow on Twitter @Jeff_McLane.