He began his pro career in the National Football League (NFL) with the San Diego Chargers, Green Bay Packers, and Washington Redskins.

[2] In an offense featuring Heisman Trophy-winning quarterback Eric Crouch, he led the Big 12 Conference with 1,299 rushing yards and scored 15 touchdowns while sharing time with Thunder Collins.

[5] Diedrick finished his four-year career at Nebraska with 502 carries for 2,745 yards and 26 touchdowns,[1] and earned his undergraduate criminal justice degree with a 3.165 cumulative GPA in 2001.

Diedrick scored his first career touchdown on an improbable play against the Toronto Argonauts on October 29, 2010, when Alouettes kicker Damon Duval missed a potentially game-winning field goal which was kicked back and forth out of the end zone until it was eventually fumbled and recovered by Diedrick for the game-winning touchdown.

[16] He played in four games that year, but his professional football career came to an end during the 2014 season when he was diagnosed with hepatosplenic gamma-delta T-cell lymphoma.

[12][17] After having his enlarged spleen removed in August 2015 and multiple rounds of chemotherapy, Diedrick underwent a stem cell transplantation in June 2016 with his daughter, Dominique, serving as the donor.

His health returned, and he spent the 2017 season as a strength and conditioning coach for the Toronto Argonauts,[18] winning his fourth Grey Cup.

[5] Diedrick died from hepatosplenic gamma-delta T-cell lymphoma at Toronto General Hospital on June 24, 2023, aged 44.