Chip Kelly's offense is right there on television every week for viewers to watch and now on NFL.com for fans to dissect, using the coach's film if they pay a yearly fee.
But what kind of play-caller is the Eagles coach?
"I think all play-callers tend be quick thinkers," Eagles offensive coordinator Pat Shurmur said, "which of course he is."
Kelly's up-tempo offense can often move at a frenetic pace. To speed up the process, plays are sent in via one word or two- or three-word phrases. But Kelly always seems to be one step ahead of opposing defensive coordinators.
"It's just his feel for the game," Eagles quarterback Michael Vick said. "I don't think he purposely tries to be fast with his play-calling and his tempo. I think he just knows exactly what he wants next and that's what makes him so efficient."
As much as Kelly says his play-calling counters how a defense schemes his offense, practice squad quarterback G.J. Kinne said his secret is in the week of preparation before a game.
"We go over so much what we're going to do, we almost know what he's going to call," Kinne said. "He gives [starting quarterback] Nick [Foles] a lot of confidence out there because we've rehearsed so many times and he's right on with his calls."
Kelly first started calling plays in 1999 when he was in his first season as the offensive coordinator at New Hampshire. Like any skill, it developed over time. His meteoric rise from New Hampshire to Oregon to the Eagles suggests that he must be improving, but he was recently asked if he liked where he was as a play-caller.
"I'd better like where I am now, because this is where I am," Kelly said. "I've always believed play calling is based on your personnel. You're trying to get your players in positions to make plays, and you have good days and bad days, just like players have good days and bad days."
Kinne said that Kelly had a rare gift for being able to read a defense from the sideline. While all play-calling head coaches work from the sidelines, the NFL has more offensive coordinators call plays from the coaches' booth.
Kelly said he only called plays from upstairs during his two seasons as Oregon's offensive coordinator. Shurmur, who calls all the plays during the week of practice, watches from above.