The phantom and YB can really mess up the pattern. That and sometimes sterlings can already have a jumbled and faded pattern. The eyestripe are also very pronounced which generally doesn't happen in super cinny.
Do you know what the parents were? Because that would be the other way to figure out the possibility of something else causing it. I'm actually going to be trying to prove out sandblast in my pewter next season.
He may stay a little on the grey side, but honestly I would expect some browning. The color change on my boys has been crazy and phantom is a bit more of a dark and brown gene in some combos