Mitchell's participation in training camp could be limited in the early going while he deals with migraines, Adrian Dater of the Denver Post reports. The Avalanche have already announced that the migraines aren't related to the Apr. 11 concussion the center suffered, knocking him out of the remainder of the postseason. While that sounds like a bit of fortunate news, Mitchell could still be held out of the team's first few preseason games as a precaution. Mitchell is likely poised to open the regular season as the team's third-line center.