Outside of Alex Smith, you're unlikely to find a more controversial player in the comments section of this site than Knile Davis.

On the surface that seems a tad absurd. A backup running back isn't exactly the most important position in the world. It seems about as silly as arguing about backup quarterback or a fifth string corner (what do you MEAN we do that too?). But put Knile Davis's name in a column and you're likely to see opinions vary from "Knile is one of the best backup running backs in the NFL" to "Knile sucks and should be replaced."

Obviously, opinions are bound to vary on any given player. However, in the case of Knile Davis, we're in a unique situation. What makes it unique is that both sides are kinda absolutely right AND absolutely wrong at the exact same time. I know, it makes my brain hurt too.

Davis is a fascinating case study. On one hand, he really IS capable of making explosive plays that almost no other running backs in the league are able to pull off (we'll get back to the word "making" in that sentence shortly). On the other hand, he gets tackled at or behind the line of scrimmage more often than nearly any other running back I've ever seen.

What it comes down to is that Knile Davis is a a freaking SPECIMEN of a human being. Even in the NFL he stands out. He's built like a power back but has the acceleration and long speed of a speed back. When you weigh nearly 230 pounds you're not supposed to run a 40 under 4.4 seconds. It's just unnatural. There are few players who are unique athletes at the NFL level, and Davis is one of them.

I'd argue he's the most "boom or bust" runner on a carry by carry basis in the league. When the play goes as planned blocking-wise he can do better than all but some of the best runners in the league. When things break down?

That combination of speed, burst, and size make Davis difficult to stop when he's got a head of steam and is running with authority. He has, at times, absolutely laid out defensive players in a way that makes you a little uncomfortable (kind of like that last much MMA fighters get in when a guy is out before the ref can call the fight and jump in). Seriously, click that link. You see what happens when a 200 pound man hits a 230 pound man who can run like Davis does.

Those snaps (where Davis has a hole to run through and hits it with authority) make you think that he could absolutely be one of the better runners in the NFL.

Then there's those other snaps. You know, the ones where he doesn't have a clear lane immediately apparent when he gets the ball. On 90 percent of those snaps Davis looks like a totally different runner. It's somewhat maddening. And by "somewhat," I mean I've broken three laptops just reviewing the film for this article.

This dichotomy is why Davis is currently controversial. I'd argue he's the most "boom or bust" runner on a carry by carry basis in the league. When the play goes as planned blocking-wise he can do better than all but some of the best runners in the league. When things break down? He's very, very poor at compensating and runs with significantly less authority, dancing around and going down easy.

We'll look at a play that represents each of type of Knile Davis play to try and demonstrate this dual personality thing he's got going. We might as well start with the kind of run that makes us sigh and shake our head.

This play is going to be a simple handoff to the left side out of a 2 TE set, a stretch play the Chiefs run multiple times a game from various formations.

I believe the initial call is for Davis to try and get around the edge to the outside (I say "I believe" because I wasn't in the huddle. One of my pet peeves is when people assume they know for a fact what play calls were). Unfortunately, things don't quite work out as I imagine the play was drawn up.

Things are going "OK" out of the gate, but there's a major problem that's about to develop. First of all, asking Mike McGlynn to pull and cover as much space as this run requires is an issue. That just wasn't something McGlynn was good at (as maligned as Jeff Allen has been at times, he does a solid job on these zone stretch plays getting into space quickly). He's got a WAYS to go and Knile is going to catch him quickly.

The real problem, though, is that Miami's linebacker (No. 53) has very quickly diagnosed the play for what it is, and rather than trying to rush the gap between Eric Fisher and Anthony Fasano (which would allow McGlynn to take a shorter path to the block) he's heading for the edge to seal it. Really nice job of recognition by that defender, and that creates a problem.

McGlynn still hasn't been able to get a body on the linebacker, who is smartly sticking to the edge, knowing that he has help inside as long as Davis can't turn the corner on the defense.

On the other hand, as often happens on these zone runs, another hole has opened up along the line as every Chief but McGlynn has been able to get a hat on someone (well, other than Travis Kelce, whose cut block did the job of slowing his guy up but didn't take him to the ground). That lane is more of a straight ahead endeavor and isn't likely to be a huge play, but there's room there to lower your head and plow forward for 4-5 yards.

What makes Jamaal Charles so brilliant at these plays is that he would be in that lane immediately and would quite likely recognize that No. 53 for the Dolphins has committed himself too far outside to help if he makes a cut left after hitting the hole. That's the only possibility for a big play here, but Charles is a guy who can make that play happen. The reason the Chiefs run so many plays like this is that Charles is able to pick the best open lane in a heartbeat and capitalize on whatever the defense does once he picks that lane.

That skill (the often talked about "vision") is rare at an elite level, and it's not one a lot of backs have. Davis absolutely does not. However, he SHOULD have the wherewithal to take the inside lane and (as I mentioned before) just power his way for some yardage. He's a big, strong back who moves piles when he runs with purpose.

So to be clear, I'm not expecting Davis to make a Jamaal play here. That's an impossible burden to meet for almost any back. What I'm expecting is that Davis recognize the clear running lane for 4-5 yards and plow through, using that 230 pound frame.

Instead, Davis does pretty much the opposite.

Knile decides the best course of action is to try and pull a LeSean McCoy-style field reversal. He halts (maddeningly, right in front of the lane he's got) and heads back toward the middle of the field after seeing (I THINK) that the outside edge has been contained and the run isn't going as drawn up.

Of course, the problem is that in the NFL you can't go off script quite THAT much as a runner. Defenders are too good. They recognize plays quickly and are so, so fast. This results in them swarming to the ball at a frightening pace. Davis is a victim to the swarm pretty much immediately after he tries to reverse field and is buried in the pile.

All Davis had to do was run with authority in the lane that was cleared and this play would have been notched in the "minor win" column. Instead, it goes down as a stuff.

This is a great example of how Davis runs when his (seeming) first option isn't open. His running completely changes. He becomes more tentative and tries to outrun or out-juke defenders when what he SHOULD be trying to do is simply run them over (or bring a few of them with him on his way to falling forward for a few yards).

Think of this issue like a rookie quarterback who is too reliant on his star WR. If that option isn't open he panics and takes off running, never recognizing the other open guys on the field. When Davis doesn't get the blocking he was expecting at the snap, his whole mentality as a runner changes and he becomes a bottom quarter of the league running back.

It's not a matter of being afraid to be physical. We can tell that much simply by looking at a play where things DID go as drawn up.

Here we've got some old school smashmouth football. the Chiefs line up with three tight ends against the Rams (I love these sets. I love them. I hope Harris is healthy and Shag explodes so we can see more of them) and Davis is to run up the "middle" of the stacked line, between the RG and RT.

There's nothing fancy going on here. No extra reads to make, no additional options to consider. It's a very straightforward "we'll have our guys line up hit someone, and you run through the hole."

And as you can see here...

... it worked. Everyone does their job and a lane is created for Davis to run through. In this case, there's no hesitation whatsoever on Davis's part.

Now, this might be where you say "well, crap, of course he didn't hesitate. He had a highway to run through." To an extent I can agree. However, by the time Davis actually hits the hole (he's a couple yards behind the LOS in this screenshot) the lane had shrunk considerably. That's the nature of the beast in the NFL. Again, defenders are really, really good.

By the time Davis runs through the hole it's actually a little smaller than the lane he turned down in the first play we looked at. "But why would Davis take that lane but not the first one," you ask? This is where my theory on Davis comes into play. He's willing to be physical and try and slip (or power) his way through small lanes, but it's his first "read" that he goes to. Past that read he's just ... well, from what I can see he doesn't see past that first read.

The difference in the way Davis runs on a play like this (a power blocking play in which he knows exactly where he's going) and a play like the first one we discussed (a zone blocking play where he has to make fast decisions) is unbelievable. I demonstrated above Davis's refusal to duck his head and power forward for a few yards, instead trying to dance around defenders and getting buried.

On this play, Davis does the exact opposite, sprinting through the gap and then lowering his shoulder into the first defender he encounters. And wow, does he get results. Look at where he makes contact with the defender versus where he's brought down. The red line is the 10-yard line in each picture (sorry about the quality of picture, NFL Rewind was not cooperating)

Davis gains a full five yards after initial contact there, completely plowing over some poor secondary player (something he does more often than I'd remembered, by the way) and dragging a linebacker a couple of yards with said poor secondary player hanging onto his leg like a child trying to get carried to bed instead of walking.

Don't tell me Davis can't run physical. He absolutely can, and has. He has delivered SHOTS to players when he's running like he is in the picture above.

The problem is he doesn't always run like he does there. It's very, very situation specific. When Davis has a clear lane to run through he does so with a ton of aggression, speed, and power. When Davis lacks a clear lane to run through he is timid, dancing, and indecisive. It's night and day.

You know what comparison kept jumping out at me (and was suggested by some on Twitter)? You're not gonna like it, to be perfectly frank. But what Davis really reminds me of is a more explosive Larry Johnson. We joke about him now and call him 2.7, but for a time Johnson was a very effective back ... when running behind an exceptional run-blocking offensive line (and the Richardson / Dunn combo that still stands as the best blocking FB / TE combo ever).

When Johnson didn't get good blocking he often just ran into the backs of his linemen, defaulting to his power to try and force extra yardage (and when he was running angry enough he pulled it off occasionally). Davis is the same when his blocking fails, defaulting to his best trait; except in his case his best trait is his speed, so he attempts to try and run away from contact rather than toward it.

When Davis has a clear lane to run through he does so with a ton of aggression, speed, and power. When Davis lacks a clear lane to run through he is timid, dancing, and indecisive. It's night and day.

And that last sentence is the biggest problem I have with Davis. If he defaulted to lowering his head and trying to grind out a few yards when his blocking failed, he'd be a significantly better running back because he'd get 2-3 yards instead of 0-1 yards on those plays. What's more, with Davis's unique size and speed, he'd have a puncher's chance at more than 2-3 yards every time he took a shot. He is truly that physically gifted.

Until Davis accepts his fate as an incredibly fast power back, he's going to struggle with consistency at the NFL level (barring a massive improvement in his vision, which seems... unlikely?). He's got the physical tools to be a guy defenses hate playing, but he needs to look in the mirror and decide it's time to stop being a "speed back." If he's willing to give up on the dream he could well become one of the most overqualified power backs the NFL has seen in quite some time.

So whether you say "Knile Davis is one of the best backup running backs in the NFL and could be a star on some teams," or "Knile Davis is terrible and doesn't know how to play running back," you've got a shot at being right. it just depends on which snap it is. I'm hoping with some improvement in the run blocking, we'll be seeing more of the boom and less of the bust on Davis's carries this season.