ENGLEWOOD, Colo. --In my years tweeting, I've been asked thousands of questions. But when you're limited to 140 characters -- punctuation and spaces included -- some answers will be inadequate.

First up, one of my favorite Broncos fans, checking in from the English city of Rotherham, in South Yorkshire:

This is such an outstanding question, I stewed on it a bit during a recent trip while driving from Atlanta, Ga. to Asheville, N.C. and back.

First, the running backs. They've slipped in draft value, but it doesn't mean they've diminished in importance. What teams have learned, however, is that the cost-benefit ratio on running backs is often better from the second round onward, given the position's relatively short career span and peak effectiveness. Drafting a running back every year isn't the worst idea to ensure you always have a fresh possibility at a position where the attrition is highest; that was how the Broncos were able to crank out one 1,000-yard running back after another from 1995 to 2006, because they kept picking runners even when it was not a position of need. It didn't always work -- do the names L.T. Levine or Ahmaad Galloway ring a bell? -- but the successes of Terrell Davis, Olandis Gary and Mike Anderson, all late-round picks, were enough to compel the Broncos to keep tapping the well.

You can win with a low per-carry average -- the Broncos did that last year, with just 3.8 yards per rush -- but you won't win very often with a ground game that fails to get first downs. Denver's first-down percentage was eighth (30.7 percent of the team's carries moved the sticks). The league's top nine teams in this category included seven playoff teams; the bottom nine had just one (Atlanta). The 2011 Giants are cited as a team that couldn't run but could still won the title; they were last in the league in rushing yardage, but also 21st in first-down percentage, placing them at the bottom rung of the league's middle class. First-down percentage is like on-base percentage in baseball; it's not a be-all, end-all, but it's a simple, key measure of the primary task: for the ground game, it's chewing up the clock and keeping the ball from the opponent.

Now, the defensive perspective and why you want run-stuffing tackles to break down a foe's ground game. Their value is obvious, since you want to do everything you can to make your opponent one-dimensional. If those massive defensive tackles can help eliminate the run as a viable option, you've cut your foe's playbook down by as much as half -- and, if your defense is constructed properly, forced an offense to attack your strength. Thus, to make run defense work to create a winner, you still need some competence in pass coverage, otherwise, you're simply steering an opposing offense to the smoothest possible road.

Look no further than last year's Tampa Bay Buccaneers for evidence. The Bucs led the league in yardage per carry allowed, but also led in another vital statistic: first-down percentage allowed, as just 22.8 percent of the carries against them moved the sticks.

Since running was ineffective against the Bucs, teams abandoned it. Only two teams allowed fewer carries than Tampa Bay's 377 in 2012. Tampa Bay's cornerback corps was decimated, and the Bucs were at or near the bottom of the league's defensive rankings in yardage per attempt, completion percentage allowed, sack ratio and quarterback rating allowed. The Bucs were the only team to rank in the bottom six in all of those categories; having the best run defense and an above-average rushing offense meant nothing.

The Broncos were the opposite.

Although the re-signing of defensive tackle Kevin Vickerson and the addition of ex-Jaguar Terrance Knighton were important to the Broncos' run defense up front, much of their heavy financial investment defensively is to defend the pass, chiefly in the form of Champ Bailey, Von Miller, Dominique Rodgers-Cromartie and Wesley Woodyard. Woodyard, in particular, provides needed versatility; which is why he was the only NFL player with at least 100 tackles, five sacks and three interceptions last year. 

The plan worked last year; Denver's defense ranked second in yardage per carry (3.6), and usually forced teams into pass-intensive mode, which is how you end up with two double-digit sackers who make the Pro Bowl. It worked for other postseason teams, albeit to a lesser degree. Still, six of the nine teams to allow less than 4.00 yards per carry last year made the playoffs. 

Stout run defense is no guarantee of success, but it does help your chances. Since 2000, teams that allowed less than 3.75 yards per carry made the postseason 47.9 percent of the time. The postseason qualification rate dropped for teams in the 3.75-3.99 range (44.4 percent), 4-4.24 (33.8 percent), 4.25-4.49 (32.9 percent) and 4.5 and up (27.5 percent).

Other positions will be of higher financial and draft value. But those dedicated to running and stopping the run won't ever fall completely out of fashion -- not as long as a competent run defense increases your odds of being among the last teams standing.