172 shirt sales this time last year vs 419 shirts sales this year, at roughly 50 quid a pop?Not sure that's a barometer of happiness.
If we're talking shirt sales (which just so happens to be the basis of this thread) then the manufacturer of the previous kits does have a direct impact upon sales. If the new kit had been made by Nike or Adidas then it would be higher than the current Under Armour sales. It's really not a hard concept to understand.