What has happened to the Buffalo Bills vaunted defense?

After a 4-0 start, the Buffalo Bills have dropped two consecutive games.

Following Sunday’s action and entering Monday’s clash with the defending Super Bowl champions, Sean McDermott’s 4-1 Buffalo Bills ranked 19th in the NFL in total yards per game allowed (371.8 average).

Leslie Frazier’s defenders ranked a respectable 11th in the league in rushing defense — surrendering 108.6 yards per game on the ground — while only eight teams were allowing more passing yards per contest (263.2). The team had already allowed 17 offensive touchdowns in their first five contests.

It’s a dramatic departure from a year ago when only the New England Patriots and San Francisco 49ers allowed fewer total yards per game (298.3). McDermott’s club gave up just 27 offensive touchdowns and a total of 259 points during the team’s 10-6 showing.

Unfortunately for the current AFC East leaders, things only got worse in the team’s 26-17 home setback to the Kansas City Chiefs (via John Wawrow of the Washington Post). That makes it two straight losses for a club that won its first four games.

The Buffalo Bills defense hasn’t been a formidable force.

The Bills have been outscored a combined 68-33 the past seven days by the Tennessee Titans (42-16) and Chiefs, respectively. Against Andy Reid’s club, Buffalo was rolled for 466 total yards – including a disturbing 245 on the ground (161 by Chiefs’ rookie Clyde Edwards-Helaire).

McDermott’s squad sacked Patrick Mahomes only once and forced only one turnover. The Bills have now totaled just seven takeaways and 11 quarterback traps in their first six contests while allowing 28 points per game and opposing offenses to reach the end zone 20 times.

This season, Buffalo Bills’ third-year quarterback Josh Allen has made significant improvements. And with the team able to consistently score points, this side of the ball would finally compliment Frazier’s defense.

But things have gone sideways for a unit that was supposedly bolstered by the additions of veterans such as cornerback Josh Norman, linebacker A.J. Klein and defensive linemen Mario Addison and Vernon Butler — all familiar with McDermott’s system during all of their days in Carolina. But it hasn’t jelled to date. Fortunately, the Bills still have 10 games to figure it out.