Drafted in the fourth round (118th overall) of the 2001 NFL Draft out of Northern Illinois, Ryan Diem arrived in Indianapolis as a powerful, 6-foot-6 interior prospect who quickly carved out a permanent home on the edge. After proving his mettle as a rotational guard in his debut season, Diem transitioned full-time to right tackle in 2002, securing a starting position he held with exceptional consistency for a decade.

Operating on the strong side of one of the most prolific offenses in pro football history, Diem provided crucial edge protection for Peyton Manning's lightning-fast pre-snap rhythm. Possessing a wide base and heavy hands, he locked down pass rushers while setting a physical edge for Edgerrin James and Joseph Addai in Howard Mudd’s zone-blocking scheme. While high-profile national awards often overlooked right tackles of his era, Diem’s steady reliability in pass sets allowed Manning to operate with complete comfort inside the pocket.

Diem’s quiet dominance was a cornerstone of Indianapolis' golden championship era. He anchored the right side of the front five throughout the 2006 postseason, culminating in a stellar blocking performance in the rain at Super Bowl XLI to help secure a 29–17 victory over the Chicago Bears and bring the Lombardi Trophy to Indianapolis.

Durable and unselfish across 11 NFL seasons, he retired after the 2011 season.  Diem appeared in 157 regular-season games and made 150 starts in horseshoe blue, routinely battling through injuries to keep the Colts' high-octane offense operating at peak efficiency.