Apparently the definition of "original poisition of the ball" in the blocking beow the waist rule is not what we were used to thinking of in days gone by. That "spot" was actually a line that ran through the long axis of the ball, parallel to the sideline, all the way to the endline (N-S line). I am told that now that really does refer to a spot (or a general area anyway). This came out at the CFO West clinic this weekend. Is that what you are hearing in other parts of the country?
This would make a"crackback" within the first few yards of the line of scrimmage illegal if done by a restricted blocker but legal if done further downfield , i.e. 5 or more yards.