The rockers are supplied and designed with a chrome plated "wearing" face. It's this chrome surface, where it contacts the cam lobes that "flakes", or completely wears through.
When this happens, the rocker base material wears away and the clearances open up. The base material also starts to wear away at the cam lobes.
Result is, that if left, not only will the rockers be junk but also the cams. The it REALLY gets expensive
