Although, it's not that hard to believe. Many many offensive linemen come from top-tier schools (like Fleener, who went to Stanford) and it's becoming more common for QB's to do this as well (like Andrew Luck, who went to, well... Stanford).

Although, it's interesting that in the average scores, the "skill" positions (WR, FB, HB, etc.) all have lower averages than the non-skill positions.