2006-07: Eller was one of the top players in the under-20 elite league in Sweden. In 39 games, he scored 55 points with Frolunda, who were the junior league champions. He was one of his team’s best defensive players, and played with a physical edge as well, ranking third in penalty minutes. Eller performed admirably at international junior competitions with the Danish national team when called upon, as well.
2007-08: Eller had quite the 2007-08 season. The center started off with Boras HC (SWE-2), where he recorded two goals and six assists in 19 games. He was then moved to Frolunda HC Goteborg Jr. (SWE-Jr.), where he appeared in nine games, recording eight points (4g+4a), before he was moved up to Frolunda’s senior club for 14 games. Eller was also chosen to represent Team Denmark at the WJC, where he recorded six points (3g+3a) in as many games. He also saw action with Denmark’s senior club at the WC, appearing in another six games and recording two helpers.
2009-10: Eller had his first taste of pro hockey, with 57 points in 70 games with Peoria of the AHL. He was also given a brief stint with the Blues, tallying 2 goals in 7 games. Following the season, Eller was dealt to Montreal for Jaroslav Halak.