Unfortunately this is flawed because of the issue of self-selection.
The players who win are more likely to stay at a table and at a site for longer than those who are losing. And if you aren't capturing the majority of hands played on a site then you don't know what happens next.
There is another issue. Imagine 2 sorts of player - one rebuys at any table where he gets stacked.The other decides from experience that with his image shot and possibly being outplayed he would prefer to open a fresh table (usually one you aren't logging). The second player will often look like he is one of the <100 hand donks to you and the first won't - but they may well each be equal winners and losers
See the attempt to work around this problem in the PT autorate article as I compare the 'persistence' of player types (ie their differing drop out rates) over different nos of hands logged.
http://www.andymcnish.btinternet.co.uk/newauto.htm
I supect you are quite right in your theory btw, I just dont think your numbers 'prove' it as well as you think.