Why do you think it's an excuse?
I've owned my EV2 since October 2004 and tried it with pretty well every make of pellet that is on the market. After thousands of rounds, the consistent picture that emerges is that tight fit pellets do not group as well as looser fit. Whether that is due to deformation as they are seated by the probe, or details of the barrel choke, I don't know, and frankly does that matter?
Regarding the stated size of pellet, that is a red herring. One of the best pellets in this rifle is the JSB Exact Express and on the tin it says 4.52. One of the worst is the Bisley Magnum. Every one of those feels tight on loading.
After nine years I think I have a reasonable grasp of how this gun shoots.
My trophy cabinet only has one BFTA goblet as I don't take part in the national scene in FT.