2008-09: Mueller attended camp with the Colorado Avalanche but was not signed to a contract. He opened the season with Colorado's AHL affiliate Lake Erie and, after a brief demotion to the ECHL, skated in 59 games for the Monsters in his first pro season. He scored 5 goals with 11 assists and was +1 with 23 PMs as an AHL rookie. Lake Erie missed the playoffs, finishing sixth in the North Division. In his brief three-game stint with ECHL Johnstown Mueller scored 3 goals with 3 assists and was +2.
2009-10: After opening the season in the ECHL with Cincinnati, Mueller joined the Predators' AHL affiliate Milwaukee at the end of October and skated in 67 games for the Admirals. He scored 13 goals with 14 assists and was +10 with 37 PMs. In the Admirals seven-game playoff series with Chicago he scored 3 goals with 2 assists and was -1 with 4 PMs. Mueller scored 4 goals with 1 assist in five ECHL games with Cincinnati.
2010-11: Mueller signed his first NHL contract, a one-year, two-way contract with the Nashville Predators, and made his NHL debut in December 2010. A free agent invitee to Predators' camp, he was released and signed to an AHL contract by Milwaukee. When the Predators experienced a rash of injuries center, Mueller was signed and spent just over a month with Nashville. He had 3 assists and was an even plus/minus with 2 PMs, averaging almost nine minutes of ice time in 15 games. He was the leading scorer for AHL Milwaukee despite skating in just 67 of 80 games for the Admirals – scoring 24 goals with 26 assists. He had a +7 plus/minus and garnered 34 PMs. The Admirals reached the second round of the playoffs after finishing first in the West Division. In 13 playoff games Mueller scored 4 goals with 7 assists and was +3 with 13 PMs. He was re-signed by the Predators as a restricted free agent to a one-year contract in July 2011.