Head coach Chip Kelly might be woken up from his sleep tonight by the sound of a referee's whistle signaling another flag.

There were 21 accepted penalties in Friday night's 42-35 loss to the New England Patriots. New England incurred a slight majority of those flags (11-10), but that doesn't provide a plausible excuse in Kelly's mind for his team's lack of discipline.

"If you can't play within the rules, you can't play in this league. That's just the bottom line," Kelly said. "You're just handing people first downs. We better figure it out.

"You don't have to agree with the speed limit, but if the cop's out there with a speed gun then you better take your foot off the gas or he's going to pull you over."

Kelly also expressed disappointment in his team's four turnovers on offense (two interceptions, two fumbles) as well as the third-down defense. The Patriots converted seven of their first 10 third-down chances and 10 out of 15 for the game.

"We need to generate a better pass rush," Kelly said. "I think our defensive line has to do a better job in terms of what the rush contains are."

There were plenty of positives for Kelly to take out of the game. Quarterback Nick Foles rebounded from his struggles in Chicago and completed 8 of 10 pass attempts for 81 yards and a touchdown. Backup Mark Sanchez had a second strong outing going 11 of 12 for 117 yards with two touchdowns and an interception.

"He's made us feel really comfortable about the quarterback position," Kelly said of Sanchez. "I think he's getting stronger. He's really comfortable in what we're doing. He's got a really good feel for playing quarterback. We've been really happy with him so far."

Rookie wide receiver Jordan Matthews showed Eagles fans the player who shined throughout Training Camp with nine catches (on nine targets) for 104 yards. Matthews battled drops in the preseason opener last Friday.

"He's such an emotional guy and plays at such a high level that I think he was just ramped up a little bit too much for the Chicago game," Kelly said. "The Jordan we've seen in practices is the Jordan that you kind of saw today."

Matthews' performance was encouraging considering that the Eagles were without starters Jeremy Maclin (hamstring) and Riley Cooper (foot) and fellow rookie Josh Huff exited the game after suffering a shoulder injury on a kickoff return.

The Eagles return to the NovaCare Complex on Sunday as the team begins prep for the critical third preseason game Thursday against the Steelers at Lincoln Financial Field. Kelly said that Cooper will practice and Maclin could return, but he didn't know about the status of Huff immediately after the game.