I'm not a huge Kerry Joseph fan, but the one thing he did well last year was manage the game and let the Rider D take over. In T.O. he had to win games on his own and he's not able to do that. Maybe on past Argo teams he could have stepped in and had the same success, but this year their defence was a step behind.
Bishop on the other hand has a tendency to force things and throw picks. His INT-TD ratio is ugly. Durant or Jyles MAY have done better, but both are unproven and had their opportunities to lead the club this season.
So the question has to be asked ... if Tillman had bucked up to keep Joseph, are they still defending champs today?