Julio Jones caught six passes for 108 yards and two touchdowns as the Falcons routed Kansas City 40-24. (US Presswire)

The Falcons' offense exploded for 376 yards on Sunday, as Atlanta won its first regular-season opener since 2009. Matt Ryan and Julio Jones connected on six catches for 108 yards and two touchdowns, as the Falcons routed the Chiefs 40-24 at Arrowhead Stadium. 

Koetter opens season on aggressive note: Former offensive coordinator Mike Mularkey, now with Jacksonville, was often maligned for being too conservative as he continued to rely on Michael Turner last year despite the Falcons having such talented receivers. New offensive coordinator Dirk Koetter unleashed aggressive play calls  as evidenced by the 17 passing first downs the Falcons had compared to just four rushing first downs.

Koetter atttacked on a depleted Chiefs secondary (Brandon Flowers was out) and signaled Matt Ryan to throw on 56 percent of Atlanta’s plays. Ryan, who finished with 299 passing yards and three touchdowns, hit seven receivers in total, including six catches each for Julio Jones (108 yards) and Roddy White (87). Koetter installed numerous screen plays throughout the preseason and unveiled them for Jones and White on Sunday. 

“If you are going to single me, we just try to take the matchups,” Jones said to Orlando Ledbetter of The Atlanta Journal Constitution. “You can’t double all three of us. They started out by doubling Tony [Gonzalez] and Roddy so I had the one-on-one.”

Nolan’s half-time adjustments key to victory: The Falcons’ biggest offseason moves occurred on the coaching staff as opposed to the roster. Nolan’s debut as the team’s new defensive coordinator didn’t start too hot but the offense clicked so well it bought time for Nolan to adjust his schemes. The Chiefs matched the Falcons’ high-powered offense in the first half, scoring on each possession to enter halftime down 20-17. But Nolan, who pledged to deploy a more aggressive defense, brought more pressure in the second half, giving the Chiefs’ wideouts less time to break from Atlanta’s secondary.

“We came out real slow, real sluggish at the beginning of the game,” said defensive end John Abraham, who forced one of three turnovers. “We came into halftime talking to each other and said that this is not the kind of defense we are. We came to play our defense [in the second half] causing turnovers.

Were it not for a meaningless Chiefs touchdown with three minutes left, Atlanta would’ve held the Chiefs scoreless for the last two quarters. Before the drive, the defense had permitted just 99 second half yards after getting torched for 211 yards in the first half. 

Falcons starting CB Brent Grimes is out for season: Grimes injured his Achilles tendon in the fourth quarter of Sunday’s win and will need surgery. He was placed on the injured reserve list.

“Obviously it hurts our depth anytime you lose a player of that caliber,” coach Mike Smith said to Ledbetter. “Since we’ve been here, he’s been a cornerstone at the position.” 

Asante Samuel, acquired in the offseason, will start with Dunta Robinson at cornerback leaving Chris Owens to likely fill the hole in nickel coverage. 

“How we configure this is something we’ll discuss over the next several days. We’ve got a lot of flexibility in terms of our secondary,” Smith said. 

Falcons cut down on penalties: Atlanta had 37 penalties throughout the exhibition season, tied for the third-most in the NFL but against the Chiefs, the Falcons committed just two penalties for 12 yards. Last season the team committed just 93 penalties, the 10th fewest in the league.

For more Falcons coverage, follow Mike Singer @CBSFalcons.