T. J. Oshie,[2][3] Berglund became a scoring threat in St. Louis' surprise 2008–09 season, finishing the year with 21 goals and 26 assists for 47 points in 76 games.

[12] At the time of the suspension, Berglund had missed the previous two games with what was said to be an illness, but Sabres' head coach, Phil Housley, commented that "obviously it developed into something different.

[14] Berglund later said in an interview that he was no longer happy playing professional hockey and was taking a hiatus from the game to improve his mental health.

On 1 July 2019, Berglund returned to resume his professional career in Sweden, agreeing to a one-year contract with Djurgårdens IF of the SHL.

As a free agent and speculation of a return to the NHL, Berglund opted to remain in Sweden, agreeing to a two-year contract with Brynäs IF on 15 July 2020.