Johnny Manziel comes across as somewhat of a knucklehead for some of his off-field behavior, but he might actually be more intelligent than you think.
According to former NFL scout John Middlekauff, Manziel had the highest Wonderlic score among the top quarterback prospects in the 2014 NFL draft class.
I've been told Johnny Football had the highest wonderlic test of all the top QB's in this years draft
— John Middlekauff (@JohnMiddlekauff) April 10, 2014

Middlekauff also says coaches have raved about Manziel’s intelligence:
Talked to multiple assistant coaches who have had Johnny on private team visits. All raved about his intelligence.
— John Middlekauff (@JohnMiddlekauff) April 10, 2014
Middlekauff says the average Wonderlic score for a starting quarterback in 2012 was 29 and that anything above 30 is considered outstanding. He says Manziel scored above both figures.
There will continue to be a debate about Johnny Football. Some feel he is a character risk and not suited to lead an NFL franchise. Others feel he is a special player and want him as their quarterback.
We’re sure when draft day comes that someone will take him in the top 10. We wouldn’t be surprised if the Texans took him first overall. And if you want my opinion, it’s not his character or intelligence that has me worried; it’s whether he will be durable enough for the league.