He left EVGA quite some time before starting at ASUS iirc so not the reason. As for Foxconn: I think he didn't like working himself to death, so he better left - simple, or?
Quite an interesting proof for something that was quite clear for everybody following the trends a bit. wherever sham went there was a mainboard that was pushed like nothing else:
Foxconn: BlackOps
EVGA: Classified
ASUS: RIIIE (BE), MIVE
Rule out these boards, specially for Foxconn and EVGA the trend will be gone imo. that also shows how important it is for a mfc to have a real good oc-board in the product line...