The Atlanta Falcons ' young stars delivered. The Buffalo Bills have an alarming problem.

Here's an instant reaction to the first game in a "Monday Night Football" doubleheader, a 24-14 Falcons win.

Key takeaway: Buffalo Bills defense is becoming a concern

The Bills (4-2) allowed 450 yards, including 217 on the ground. Falcons quarterback Michael Penix Jr. was 20-of-32 for 250 yards and a touchdown, and Buffalo was unable to stop young Falcons stars Bijan Robinson and Drake London. (More on them later.)

For a team with Super Bowl aspirations, the Bills defense is becoming a glaring issue. The unit has only held two of its first six opponents (New Orleans Saints, New York Jets) under 20 points and is dealing with a number of injuries.

Cornerback Christian Benford (Achilles) suffered

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