(TNS) — The most interesting thing about this Chiefs preseason is Patrick Mahomes, and you will probably agree that this is beyond debate. On Friday night, he will likely make at least one throw that none of the Chiefs' other quarterbacks could, and at least one throw that none of them would.

The most interesting thing about the regular season could be an interesting debate. Alex Smith's ability to block out noise and move past his head bouncing off the concrete turf in Indianapolis (twice). Tyreek Hill's progression as the team's No. 1 receiver. Justin Houston's knee. Derrick Johnson's return. Travis Kelce's stardom. Marcus Peters.

But the most important thing might be much more subtle, the kind of wonky football storyline that's usually glossed over in vagaries, if discussed at all.

Because aside from injuries, which can wreck any team's season, the Chiefs' only obvious potential fatal flaw is their run defense.

In an offseason absolutely packed with surprises — a big trade to draft a first-round quarterback, a successful GM fired, a respected receiver cut — the most immediately impactful move might be one that's been largely overlooked.

More on that in a minute.

In the simplest and most honest terms, the Chiefs stunk against the run last year. Only six teams gave up more rushing yards, and only eight gave up more rushing yards per carry. The problem crystallized in the playoff game, when Le'Veon Bell ran 30 times for 170 yards. Only once did the Chiefs stop him behind the line of scrimmage. Six times he ran for nine or more yards.

The Chiefs are good enough now to be judged on whether they advance in the playoffs, and feeble run defense is no way to advance in the playoffs.

"We are working our butts off," Johnson said. "I promise you we will be better in the run game this year."

Some of this, it should be said, can be blamed on injuries. Johnson and Houston are two of the team's best run defenders. They played just three full games together, and in each the Chiefs held their opponent below its season rushing average. The cumulative 3.6 yards per carry would've tied for second-best in the league over a full season.

But the Chiefs know better than to wrap themselves in a cozy blanket of excuses about injuries. Two of the teams they played with both Johnson and Houston — the Bucs and Broncos — were among the league's five worst rushing offenses.

Injuries happen, and besides: the Chiefs gave up 205 yards rushing to Jacksonville with Johnson on the field, and served as henchmen for Bell's playoff highlight tape with Houston on the field.

There were times, even before the injury, where Johnson appeared a step slower in closing gaps. Houston has played just one full season out of the last four.

Defensive coordinator Bob Sutton has spent much of training camp reminding his guys just how awful they were at stopping the run last year. Some of that is theater — football coaches are always theatrical — but most is a genuine acknowledgment that nothing else matters if they spend another playoff game dragging down a running back after the first-down marker.

But here is an inconvenient reality: this will be the Chiefs' fifth year with the same defensive coordinator, and many of the same players. They have not finished in the top half in rushing average defense even once, and only three teams have given up more yards per carry over that span.

Sutton's philosophy has generally been to create turnovers, prevent big plays and defend the pass — so in some ways, giving up yards on the ground is part of the plan.

But at least a measure of improvement will have to come if the Chiefs are going to rise above the good-not-great cycle they've been in the last four years.

So, something has to change, right? A new player, perhaps?

Oh, hey, look over there. It's Bennie Logan. He's new. And enormous. And much more athletic than he's given credit for, an alpha run stopper for a team in desperate need of one.

"I think he is going to be a real good addition," Sutton said.

"I just try my best to pretty much embarrass the guy in front of me," Logan said.

Logan is, basically, the replacement for Dontari Poe. And while Poe is a forever legend for Hungry Pig Right and the Tebow Pop Pass he is almost certainly an inferior run defender to Logan at this point in each player's career.

The Chiefs have had good depth on the defensive line, and Chris Jones could be a star. But Logan is a little different. He's proven — skins on the wall, to use one of the organization's favorite terms — and at 27 years old still young enough to produce.

Poe is freakishly gifted, but has also had major back surgery. Bad backs get worse, not better. That's true for your neighbor, and particularly true for large men whose job demands they crash into and push against other large men.

Logan provides a measure of certainty, and an above-average run defender at the point of attack for a run defense that's long been one of the league's worst.

He can't, and won't, do it by himself. But this is an upgrade, one we'll see against an opponent for the first time on Friday night.