I agree with YV, the proof of the pudding will be the perfomances and results achieved in the bread and butter league fixtures, under Levein and Kelly the players were clearly capable of raising their performance levels and competing against higher opposition in cup competition only to come crashing back down to earth when the championship fixtures resumed.
A true test of Megson's ability and influence will be if the results and performances in the cup can be replicated in the league on a consistent basis.