Part of the issue might be that he was a "Vince MacMahon guy." From what some "smart marks" have told me, Vince was giving him a ton of chances and really wanted him to succeed.
Vince has had a tumultuous year at WWE, and now is history. Gable's other Rabbi, Lesnar is also persona non grata in WWE.
Not sure who made the call, but Steveson's (presumably) two biggest backers are gone, and that may have made it easier to cut ties.