It isn't unprecedented that a football player be negatively affected by those close to him. NFL team scouts do extensive homework on the players entering the draft to try and make sure they get a good feel for the talent and character of the prospects. For Connor Cook, what we witnessed was a borderline first round talent fall into the third day due to character concerns. Or perhaps more so the character concerns of his father and his influence on his son.
Several NFL types have cited team sources that say Cook has leadership issues. One major red flag being that he wasn't voted a team captain -- a title almost exclusively reserved for the quarterback.