[jackschultz]

The group on the far left would be the defensive backs actually. That position is best suited for the little and quick guys. While receivers can, and are small (think a Wes Welker type), receivers are also enormous (Calvin Johnson). If a corner were the size of Johnson, for example, the team would put him in as a receiver since that's more valuable.

Take a look at this reddit post with more detailed information that's position based. http://www.reddit.com/r/dataisbeautiful/comments/1oh47i/heig...