I've noticed that too man. It's BS.
I was always under the impression that the way the CB system works is that whatever your level is you roll a dice from 0-x (In this case 0-40) where the 1 def would only be able to roll a 0 or 1...therefore the odds of someone with 1 def being hit a 0 by 40 attack should be around 1 in 40....which would make missing extremely rare...not constantly like it does.
I could be wrong but that's how I remember someone explaining RSC's CB system way back in like 2002.