The world champion twice shared this in an interview at the Dreamleague Season 26:

"I started playing with them about four years ago. I was tired of DOTA, with having to communicate continuously with people. I need a break because I felt my form was seriously decided compared to the previous six months.

Mira admitted that he was too tired of the life of an electronic sports athletes, so he could not continue without time to pause. He realized that he could not return to Team Spirit after this break. According to Mira, his performance decreased by emotional exhaustion, and that's why he chose to stop playing. After resting, he accepted to join the Aurora squad.

It should also be noted that Dmitry "Korb3n" Belov and other members of the Spirit team has repeatedly expressed his desire to return - but that has never happened.