Sobotka, at the completion of the 2013–14 season, became a restricted free agent, and instead of re-signing with the Blues, opted instead to sign with Avangard Omsk in the KHL on a three-year contract. When it became clear to the Blues that there was a possibility that Sobotka would be playing in the KHL, the organization filed for salary arbitration with the NHL. On 21 July 2014, Sobotka received a one-year, $2.725 million award from an arbitrator. The result of the arbitration award states that should Sobotka return to the NHL in the future, the Blues would retain his rights for one year at the amount awarded by the arbitrator; at the end of that year, he would then become an unrestricted free agent in the NHL.
On 6 January 2014, Sobotka was named to the Czech Republic's roster for the 2014 Winter Olympics in Sochi, though a leg injury sustained with St. Louis on 31 January prevented him from participating.
