He played for the San Diego Fleet of the Alliance of American Football (AAF) in 2019, and the Dallas Renegades of the XFL in 2020.

Now on a losing streak and with ailing coach Jerry Kill watching from a private box, the Gophers hoped to get back on track against Northwestern.

The last two games of the season saw Nelson and Leidner split snaps as the team lost to Michigan State and then Syracuse in the Texas Bowl on December 28, 2013.

Nelson was named the National team's MVP as he led his squad on a 14-play scoring drive in the opening series of the game.

In January 2018, Nelson signed with the Canadian Football League's Winnipeg Blue Bombers to compete for the fourth-string backup quarterback position.

[17] In the third round of the inaugural AAF QB Draft, Nelson was picked by the San Diego Fleet with the eighth selection.

After Bercovici struggled for much of the season opener against the San Antonio Commanders, Nelson relieved him late in the game, completing 5 of 10 passes for 68 yards and an interception in the 15–6 loss.

[20] The following week's matchup against the Commanders saw Nelson throw an interception on the first play before rebounding with two touchdown passes in a 31–11 San Diego victory.

[21] During the fourth game against the Memphis Express, Nelson threw a touchdown before exiting in the second quarter with a shoulder injury; he was replaced by Alex Ross as the Fleet fell 26–23.

[32] Source:[33][34] Nelson was charged with first- and third-degree assault for kicking former Minnesota State Mankato football player Isaac Kolstad in the head during the early morning hours of May 11, 2014, after a night of underage drinking.

[36] Other people around the area reported that Nelson allegedly kicked Kolstad while he was unconscious, following being punched by a third party, Trevor Shelley.

[36] Kolstad was left unable to breathe on his own following significant destruction of brain tissue and underwent surgeries.