Mental errors are something football coaches can't and shouldn't tolerate under any circumstance, regardless of the score. When players make those types of mistakes, even stars like Larry Fitzgerald are fair game. When the Cardinals were transitioning into Bruce Arians' offense, Fitz would sometimes draw the ire of the head coach when he missed an assignment. Eventually, Larry and B.A. got on the same page, and we've seen the fruits of their labor the past couple of seasons.

David Johnson is a future, if not present, NFL star, despite being a second-year player with seven career starts. Because he has all the talent in the world, he will be held to a lofty but worthy

standard. Arians was unhappy about a couple of mental errors Johnson made that cost the team points Sunday against Tampa Bay. One of those mistakes was on a pass play where he was a wide receiver matched up against a cornerback. The fact the Cardinals believe Johnson can win those matchups against defensive backs -- whether a defense is in man or zone -- speaks volumes. Arians knows to win a Super Bowl, you can't leave big plays on the field, even in a blowout win. They catch up to a team, and that's why Arians can't let them slide early in the season. Especially when you have a player like Johnson, who creates mismatches and is such a freakish athlete. 

I've heard Johnson compared to Marshall Faulk because of his pass catching ability, and also to Adrian Peterson because of his physicality. Sunday was the first time I had heard comparisons to Barry Sanders. Former linebacker, ex-Sanders teammate and current Fox analyst Chris Spielman, along with former linebacker Rob Fredrickson, who played against Sanders, talked about the similarities between the two running backs. Johnson, like Sanders, has the unique ability to stop, cut and accelerate in a short time, and in a small window.

Barry Sanders, in my opinion, is the greatest running back of all time. It's hard not to get excited about Johnson's potential when you hear two former NFL linebackers talk glowingly of Johnson. Spielman and Fredrickson have great credibility having played in a golden era of running backs, trying to tackle the likes of Sanders, Emmitt Smith and Bo Jackson. I think Arians and the Cardinals see the same potential in Johnson, which is why they can't let him settle. They can't accept mental errors of any kind at any time. Perseverance through those errors is what will help Johnson take the next step in his development.