Eerily perfect (3,4,2,2,4)
I believe the answer is:
too good to be true
(Other definitions for too good to be true that I've seen before include "So excellent it defies belief (3,4,2,2,4)" , "barely credible" , "Only apparently advantageous (3,4,2,2,4)" , "Improbably excellent (3,4,2,2,4)" , "Not nearly as excellent as appearance might suggest" .)