"I was excited to learn this system, to learn this culture, and be a contributing factor to a team that's really on the rise," Musgrave said. "I enjoy contributing, whether it's a broader responsibility or a honed-in one."
Musgrave, who called plays for the Eagles late in the 1998 season when he was in his second year as an assistant coach, has not yet mastered Kelly's system. Foles has helped coach Musgrave even while Musgrave coaches Foles.
"I've probably had as many, or more, questions for Nick earlier this spring as he did for me," Musgrave said.
The relationship between a quarterback and his position coach is an important one. Nine current NFL head coaches were once quarterbacks coaches in the league. In 1999, the Eagles hired Packers quarterbacks coach Andy Reid to be a head coach.
Musgrave inherits Foles after the quarterback's standout season, which included 27 touchdowns and only two interceptions. Musgrave has already identified areas for Foles to improve: throwing the ball earlier in downs, avoiding big hits, staying healthy, and using his legs.
"Musgrave's been awesome," Foles said. "He's a different coach than Lazor. . . . Different fundamentals, different things when we're out there. Just different coaching styles."
One new drill has Musgrave wearing a baseball glove. The reason he does this is to ensure that Foles and the other quarterbacks can throw hard instead of instinctively easing a pass because Musgrave is older. He also has stacked trash cans six feet high in the corners of the end zone to simulate a receiver during drills.
Musgrave previously coached Philadelphia-area natives Matt Schaub and Matt Ryan, and compared Foles to them because of Foles' size. He also touted Foles' athleticism, mentioning the QB's prowess at golf and basketball.
Beyond Foles' physical tools, Musgrave is impressed with how quickly he processes the situation on the field and makes decisions.
"He processes things very quickly," Musgrave said. "Some guys can process what they say, and some guys invariably can't. . . . He can multitask, and it takes tenths or hundredths of a second to make a decision, which is essential."
That is a characteristic that Musgrave values. He marveled at how quickly Kelly's offense operates. His task is to try to refine a player who excelled in that offense last season - and develop Mark Sanchez and Matt Barkley behind Foles.
"It's a system that thinks players first, then plays," Musgrave said. "Which is brilliant. It doesn't mean we're going to run a certain play just because it worked in the past, but we're going to take the strength of our players and tailor the system to fit them."