The Denver Broncos have been running the ball a lot lately, as Peyton Manning's fantasy owners have surely noticed. Manning probably murdered a lot of fantasy teams last week when he attempted a mere 20 passes and did not throw a touchdown pass for the first time in over 50 games.

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While the game against the Buffalo Bills was an extreme example, astute fans have surely noticed that the Broncos have been relying on the run game a lot more in recent weeks than they did early in the season. For three consecutive games, Denver has had as many or more rushing attempts as passing attempts, which is a far cry from the offense we are used to seeing from them.

In fact, over the last three games, the Broncos are averaging 36.3 rushes per game against 29.7 passes. That means they are running the ball on 55 percent of their plays. That is substantially higher than their season average of just over 41 percent.

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So what gives? Are the Broncos suddenly a run-heavy attack?

That seems unlikely. There is speculation that Denver could be resting Manning's arm for the playoffs, which would make some sense. There are no clear indications that Manning's arm is tired or dimished in any way, and he has not appeared on Denver's injury report recently.

Still, the Broncos know that they will only go as far as Manning's arm can carry them, so perhaps they want him to be as fresh as possible for the playoffs.

Running more to rest Manning also makes some sense because it looks like the Broncos will have to play a meaningful game in week 17 this year, thus preventing them from sitting Manning to give him an extra break. The race for the top seed in the conference looks like it will come down to the wire between Denver and New England, and the Broncos will surely pull out all the stops to have home field advantage throughout the postseason.

Aside from the tired arm theory, the Broncos could simply be running more because of their depleted receiving corps. Mannings top three receivers, Julius Thomas, Demaryious Thomas, and Emmanuel Sanders, have all been battling injuries recently, so the extra running could just be the most effective way for the Broncos to keep winning while their star receivers get healthy.

Below, you can see a preview of Denver's game against San Diego this weekend.