I'm saying your time in the hobby and sample size aren't large enough to make such as strong statement.
I've had MWR boxes that have produced over 4oz silver and then follow it up with 6k without a single silver dime.
I have a feeling that CWR tend to produce more than MWR on average in general but there are two things that are lacking to make a strong statement.
1) Sample size (There are searchers who are looking in the 6 and 7 figures annually)
2) Location/provider (Which is an important factor, some places are dry, some suppliers produce and others don't, etc.)
Search through another 10k or so and you'll get a pretty good picture for your area and providers. Everyone's mileage may vary.