It's a misunderstanding that Seacrest played with vicious intent. He merely aimed to use his compact frame to establish clear breaks in action upon the game by sending careless receivers to the sideline, thereby freeing up drama-filled moments for more Coca-Cola and Ford ads to be read by the school's PA man. Eventually, Seacrest took over double duty, playing safety and PA man. The rest is television history.
(Previously on the internet, Seacrest's alleged football career has been suspiciously snarked about. Yes, linebackers, especially at the high school level, often line up at the line of scrimmage.)
This post has not been very well-populated with relevant jokes. I'll admit the only things I know about Seacrest beyond Idol and the devastating spree of mangled bodies he left behind himself on the gridiron are that he's not very tall and used to make gay jokes with Simon Cowell.