Known for his intelligence and towering size, at 6 ft 9 in (2.06 m) tall, St. Clair earned All-Pro honors nine times and is enshrined in the Pro Football Hall of Fame.

[1] Since USF did not return to field a football team for the 1952 season, St. Clair finished his college career at the University of Tulsa.

[4] Primarily an offensive tackle, he played alongside the Million Dollar Backfield, whose halfback Hugh McElhenny considered him a dominant blocker.

[7] He missed time due to an Achilles injury in 1962, but returned to play the entire 1963 season,[4][7] for which he received the 49ers' Len Eshmont Award.

[12] A perennial team captain, St. Clair was nicknamed "The Geek"[a] by his teammates due to his eccentric off-the-field behavior, including a habit of eating raw meat, which he frequently used to intimidate 49ers rookies.