Quarterbacks are a very valuable commodity in the NFL and, as such, teams are extremely aggressive in their research of said quarterbacks. This applies to all draft picks, but the stuff you see surrounding signal callers before the draft is pretty nuts. Like, for instance, a team hiring a private investigator to trail Oklahoma quarterback Baker Mayfield.

That's according to Robert Klemko of TheMMQB.com, whose done an excellent eight-part series on Mayfield thus far and reports that recently, while driving around Norman, Ok., Mayfield found out he had a tail

From Klemko's article:

Later on Tuesday, Mayfield received an alert from a trusted source that he had a tail in Norman. A private investigator, he was told, was tracking his movements on behalf of a team. The MMQB was unable to verify the identity of that team, but it should come as no surprise that any NFL franchise considering a (minimum) four-year commitment and tens of millions of dollars to a 22-year-old might like to know how he spends nights near his old stomping grounds.

Mayfield has some off-field issues in terms of his behavior for NFL teams, having been arrested previously for public intoxication back in February of 2017. Mayfield was speared by police officers on video. (If we're being honest, a college student getting drunk in public is not breaking news nor unusual, but Mayfield's too high profile for it not to be a problem at the draft/NFL level.)

An NFL team contemplating whether to invest millions and millions in Mayfield is going to want to find out what he's doing in his free time, especially with all the Johnny Manziel comparisons floating around out there, and with Manziel's struggles off the field contributing to him washing out of the NFL before his rookie contract ended.

To be clear: Mayfield is not Manziel. But it's a lazy draft time comparison that gets bandied about because of the bravado both played with while leading a Big 12 school to a high level of success. 

So what team was tailing him? 

It has to be a team at the top interested in drafting a quarterback. The Browns, Jets, Broncos, Cardinals and Saints all have visits scheduled with the quarterback. The Dolphins reportedly have a lot of interest in Mayfield too. 

Notably, per Klemko, he met privately with the Chargers. It would be something if Mayfield, who has drawn Drew Brees comparisons because of his size (Russell Wilson might be more accurate), was drafted by the Bolts to replace Philip Rivers, the guy who was drafted to replace Brees many years ago.

Mayfield also met privately with Giants quarterbacks coach Mike Shula, per Klemko.

No one knows exactly when Mayfield is going to go in the draft. He could go first overall or he could fall to the teens. But someone is going to invest highly in him, enough so that they're tailing him around campus to see what he does in his spare time.