The magazine reports that Mattrick had been offered a role that would put him in charge of a new hardware division within the company.
No further details about the proposed role have emerged, but it does not appear that it was a demotion.
Speculation had been rampant that Mattrick had been pushed after the Xbox One launch debacle. Microsoft has since retracted many of the policies that saw a negative reaction.
Analysts had placed him as the number one choice for EA’s new boss.
His decision to leave and take over Zynga was unexpected. Some commentators have said that the role is a step down, suggesting it was a last resort for the former Xbox boss.
However, sources speaking to the magazine said that he chose the role of CEO of Zynga of his own free choice.
Zynga’s hire of the former Xbox boss sent its shares up 11 per cent to $3.04.
In addition, Steve Ballmer sent a company memo that was picked up by the press wishing Mattrick the best of luck.
It is understood that Microsoft CEO Steve Ballmer is currently overseeing the Xbox division until a replacement for Mattrick can be appointed.