It won’t be a modern-day remake of the early 1960’s epic “How the West Was Won,” for sure. But after tough Sunday defeats by Kansas City and Denver, both of whom squandered meaningful leads in the kinds of games the Chiefs and Broncos once might have successfully closed out, winning the AFC West championship could come down to whichever of the longtime rivals plays the best defense in the final five weeks of the season.

And, quite possibly, which of the teams most adequately compensates for injuries on that side of the ball.

It’s not quite a battle of attrition on the defense. But after the Chiefs lost pass-rush linebackers Tamba Hali (ankle) and Justin Houston (elbow) on Sunday, and Denver was forced to play without cornerback Dominique Rodgers-Cromartie (shoulder), neither defensive unit was the same as earlier in the contests against San Diego and New England, respectively. Yeah, 17 of the 34 points the Broncos surrendered came after turnovers, including the botched punt return/fumble fiasco that allowed the Patriots to kick the winning overtime field goal. And the Chiefs also surrendered a touchdown following a giveaway.

Justin HoustonJustin Houston and his 11 sacks went down with an elbow injury Sunday vs. San Diego.

But Kansas City – which tied a league record by not allowing more than 17 points in any of its first nine games, and now has given up 68 points in consecutive losses—permitted San Diego quarterback Philip Rivers to rally the Chargers to a win after an Alex Smith-to-Dwayne Bowe touchdown pass appeared to have saved the flagging Chiefs. And the Broncos’ defense couldn’t slow the Pats at key times, either, even though the Denver defense was often forced to play with a short field.

At a time of year when defenses are relied upon to make a difference, even in a league so skewed toward offense, the signs weren’t good. And even as the Broncos and Chiefs were preparing to meet again next Sunday at Arrowhead Stadium in an AFC West rematch, the two defenses are licking some wounds.

“You’ve got to have guys step up,” noted Kansas City safety Eric Berry following the loss to the Chargers. “We can’t make excuses. We’ve got to make plays.”

Of late, at least, the once resourceful and opportunistic Kansas City defense, which seemed to pounce on every opponent mistake the first nine weeks (and frequently turned them into touchdowns), hasn’t made enough of them. The Kansas City defense, which terrorized enemy quarterbacks for months, has but one sack in its last three games, that by a blitzing Berry on Sunday afternoon. In the last four games, the unit has only two sacks. Perhaps more notable, the Chiefs could not wrestle the ball from the Chargers at all on Sunday, and have just one takeaway in back-to-back losses.

It probably wasn’t equitable that so many skeptics questioned the Chiefs’ quality after their 9-0 start. It might be fair, though, now for the inquisitors to pipe up. Not so much about the legitimacy of Kansas City, since the Chiefs seemed assured of their first postseason berth since 2010, but about how the team rebounds from its slump and from its injuries.

Dominique Rodgers-CromartieDRC exited Sunday's game against New England with a shoulder injury.

Minus Houston and Hali, who provided an outside, pincer-style pass rush and totaled 20 sacks between them, the deficiencies could become more glaring. “Those guys have made so many big plays,” Berry said. Acknowledged Rivers: “They were not the same (after the injuries).”

Neither were the Broncos after Rodgers-Cromartie, the team’s best cover corner, exited against the Pats. The Denver secondary was already depleted, especially with injuries at safety and the ongoing inability of Champ Bailey to get onto the field, and the growing M*A*S*H list is a danger sign. Who will be ambulatory for the clubs’ defenses for next Sunday’s division showdown is uncertain. The overall status of the Kansas City and Denver defenses, likewise, is tenuous.

Certainly, the high-octane Broncos are more capable of overcoming defensive losses because of their Peyton Manning-led offense. But the Denver offense suffered a fatal lull on Sunday night and the defense couldn’t rescue it. Denver currently ranks 26th in statistical defense and the Chiefs are No. 16. Both units may have to play better than their statistical perches to win the AFC West and to advance deep into the postseason. How much better they’ll be able to do so probably rests with how each responds to the injuries they’re currently confronting.

The current video-game nature of the NFL aside, defense still counts. As does the rising body-counts on defense for the two AFC West rivals.