[SSJKarma]

actually, when yoda told the emperror that he had missplaced his trust in anakin i think it was a plug to fit into the 6th movie !

afterall yoda always see's the future and he's kinda doing good at understand it.
so i say he saw that he wouldn't be able to defeat him and that LUKE would bring back his father from the darkside !
as for the fight being equal, well look at it this way... against DOKU yoda had no problem holding off DOKU's force. while he had pretty much big problems holding's off the emperror. thus force wise... the emperror was too strong for yoda ! a scene were that is evident is when the emperror is throwing off platform at yoda. the emperror had no problem throwing them off while yoda seemed to have a lot of problem holding em off. thus it prooved that yoda wasn't strong enough to defeat the emperror !