After the Denver Broncos had battled back in the second half, narrowing the Oakland Raiders' lead to 12 points with just over under nine minutes to go, returner Dwayne Harris returned the ensuing kick 72 yards.

Harris was eventually tackled on the Broncos' own 30-yard line but the return was a dagger. It set the Raiders up already in field goal range, which they managed to pound through four minutes later, extending their lead 24-9.

The Broncos would go on to add one additional touchdown with the final gun sounding at 24-16, Raiders win.

It's one thing to give up a 72-yard kick return. That's bad enough. But to relinquish it in the clutch, with the chips down, was something else entirely.

The Broncos' special teams coverage units were terrible during this summer's preseason but the hope (and expectation) was that once the 53-man roster was formulated and the players (presumably) who comprised it were actually the ones running down kicks (instead of guys who are now out of the NFL), that aspect of the third phase would improve.

Raiders KR Dwayne Harris attempts to juke Broncos' K Brandon McManus. Kelley L Cox-USA TODAY Sports

One of the reasons, likely, is that the Broncos added six non-QB players to the 53-man roster after cut-downs — guys who didn't spend one day with Denver during the offseason or summer.

And so the problem persisted, rearing its ugly head in Week 1 in a game that counted. On Friday, special teams coordinator Tom McMahon, who's been under fire in the Broncos fanbase, fell on the sword but vowed to turn the ship around.

“It's a lack of execution," McMahon said. "That's on me. Our guys [have] got to execute better. Any bad play is always on me and that's the way it's going to be. We have good players that are going to play hard, that are going to go fix it. If they goof up, that's my fault. Poor coaching and poor execution.”

It's good to stand at the podium, be accountable and take responsibility. But after two years of hearing those type of platitudes during the week, but not seeing it come out in the wash on gameday, fans are leery of coach-speak.

At this stage, though, at least when it comes to the public, all McMahon can do is promise to improve. The special-teams lapse was unacceptable to his boss, Vic Fangio, but it's not something 'unfixable'.

“We have got to do a better job coaching," Fangio said immediately following Monday night's loss. "We have got to do a better job executing. Kickoff coverage, you’re right, we had a chance there... Those are critical mistakes, areas that we got to get better in.”

With the Chicago Bears coming to town on Sunday, bringing along a returner the Broncos know well — Cordarrelle Patterson — Coach McMahon has to try to rally his troops and nip these coverage lapses in the bud, because if given even a sliver of daylight, that guy can hit the hole and be gone in no time flat.

“Extremely dangerous," McMahon said. "Cordarrelle Patterson is, we all know, he is exceptional and [Bears RB Tarik] Cohen is exceptional. We've got to do a great job. Number one, it starts with the guy that has the ball in his hands. We’ve got to do a great job as a punter, we've got to do a great job as a kicker to give us a chance to cover these things. At the end of the day, we've got to keep working vertical against these guys. If you stop and give them space back there, they'll make you miss.”

Follow Chad on Twitter @ChadNJensen and @MileHighHuddle.