How about we talk about what the thread is about?
You can't have a 4-back set in football. You have to have 7 men on the line of scrimage. You've got 5 linemen, and either 2 TEs or a TE and a WR or 2 WRs. That leaves only 4 players in the backfield including the quarterback. Aside from the impossiblility of a 4-back set, I really doubt Coach C will even use any 3-back sets. The original WCO was made to work out of only single-back sets and the modern versions, though they aren't only singlebacks anymore, don't usualy use more than 2.
Look at some 3-back sets:
TE T G C G T TE
_____QB
_HB_____HB
_____FB
TE T G C G T TE
_____QB
_____FB
_____HB
_____HB
The defense is basically forced into putting 8-9 guys in the box, simply because all of your players are there, and is pretty ineffective in any offense other than a power-option.
Excuuuuuuuuuuuuuuuse me, but isn't the quarterback considered a "back?"
Hell, I'd consider the Wishbone a 4 back set!
I think it's unlikely in the WCO, but hell, with Glenn playing H-Back, I don't see how a 4 back set is unrealistic.