Arizona Cardinals Greisen was selected by the
Arizona Cardinals in the seventh round (239th overall) of the
1999 NFL draft. As the third-string quarterback behind
Jake Plummer and
Dave Brown, he appeared in a total of five games between the 1999 and 2000 seasons, while completing 7 of his 16 pass attempts for one touchdown and no interceptions. In 2001, he was declared inactive in all of the regular-season games. In 2002, he was passed on the depth chart by rookies
Josh McCown and
Preston Parsons, leading to his release on September 1.
Washington Redskins On December 18, 2002, he was signed to the
Washington Redskins'
practice squad. He was not re-signed after the season.
Rhein Fire In 2003, he signed with the
Rhein Fire of
NFL Europe. He shared the starting quarterback position with
Nick Rolovich, playing most of the times in the second and fourth quarters of the games. He posted 76-of-131 completions for 843 yards, 10 touchdowns and 5 interceptions, while helping the team reach
World Bowl XI.
Green Bay Blizzard In 2004, Greisen joined the
af2's
Green Bay Blizzard. The af2 was the
Arena Football League's development league. He threw for 2,718 yards and 61 touchdowns.
Dallas Desperados In 2005, Greisen signed a two-year contract with the AFL's
Dallas Desperados, to serve as the team's backup behind
Clint Stoerner and later
Clint Dolezel. In two seasons, he threw 11-of-16 completions for 142 yards, 3 touchdowns and no interceptions. Greisen became a free agent after the 2006 season.
Georgia Force In 2007, Greisen signed with the
Georgia Force. The team finished the regular season with a 14–2 record and won the Southern Division championship. Georgia hosted the National Conference Championship, but lost 66–56 to the
Columbus Destroyers. On the season, Greisen completed 74 percent of his passes (393-for-531) with 117 touchdowns, 12 interceptions, and 4,871 yards. His 117 touchdowns were the AFL single season record until it was broken by
Tommy Grady in 2012 (142 touchdowns). In 2008, although the team started the year with a 3–5 mark, it finished with a 10–6 record and once again won the Southern Division championship. But after a first round bye in the playoffs, the team lost 73–70 to the
Cleveland Gladiators in the divisional round, the team's second straight home playoff loss. On the year, Greisen was 399-for-585 (68.2%), 4,956 yards, 97 touchdowns and 17 interceptions. The league folded after the 2008 season.
Florida Tuskers (first stint) On August 25, 2009, Greisen signed with the
Florida Tuskers for the inaugural season of the
United Football League (UFL). As the backup quarterback behind
Brooks Bollinger, he registered 13-of-20 completions for 116 yards and one touchdown.
Milwaukee Iron Following the conclusion of the 2009 UFL season, Greisen returned to the AFL who had resumed operations. He signed with his hometown team, the
Milwaukee Iron on January 2, 2010. He led the Iron to an 11–5 record and the Midwest Division championship. On the year, he posted a 128.2 passer rating (led the league), 382-for-563 completions (67.9%) with 107 touchdowns (second in the league) and 11 interceptions. His 5,139 yards passing broke the AFL's record for yards in a season. In the first round of the playoffs, the Iron beat the
Chicago Rush to advance to the AFL's conference championship, but lost to the
eventual ArenaBowl champion
Spokane Shock 60–57. After the 2010 season, Greisen had completed 69.9 percent of his passes in his AFL career with 15,108 yards, 324 touchdowns and 40 interceptions.
Florida Tuskers (second stint) Following the conclusion of the 2010 AFL season, Greisen re-signed with the Tuskers for the
2010 UFL season. Although he was the backup quarterback behind Brooks Bollinger again, he took over the starting position after Bollinger was injured, helping the team win the last three games. In the regular season, he posted a 97.5 passer rating, 58-for-84 completions for 664 yards, 5 touchdowns and 3 interceptions. In the
2010 UFL championship game 20–23 loss against the
Las Vegas Locomotives, he was 24-for-42 for 346 passing yards and two rushing touchdowns.
Dallas Cowboys (first stint) On December 27, 2010, he was signed by the
Dallas Cowboys' practice squad, to provide depth in case starting quarterback
Jon Kitna could not play because of an oblique muscle injury. On December 31, he was promoted to the active roster for the season finale against the
Philadelphia Eagles, in which he did not play as a backup to
Stephen McGee.
Virginia Destroyers (first stint) In 2011, Greisen returned to the UFL to play for the
Virginia Destroyers, who assumed rights over the Tuskers' players when the team folded. He officially signed with the Destroyers on June 16. In the shortened-season, Greisen led the Destroyers to a 3–1 record, with the one loss coming in the season finale against the
Sacramento Mountain Lions in a game he sat out most of due to injury. He helped lead the Destroyers to the
2011 UFL championship game, his third consecutive appearance in the UFL Championship game. Greisen completed 21 of 31 passes for 154 yards, as Virginia won the game 17–3.
Dallas Cowboys (second stint) On December 14, 2011, he was signed to the Cowboys practice squad after backup quarterback Jon Kitna was placed on the
injured reserve list with a back injury. Despite first appearing in the NFL in the 1999 season, Greisen maintained practice squad eligibility because he had been active for only eight NFL games, which was less than the nine games limit. On December 31, he was promoted to the active roster. He was declared inactive for the season finale against the
New York Giants as the team's third-string quarterback. He was not re-signed after the season.
Virginia Destroyers (second stint) On March 15, 2012, Greisen was declared a free agent. He returned to the Destroyers for the 2012 season, which was cut short due to financial shortfalls; it was his last stint in professional football. ==Coaching career==