Don't give up Michael. You should consider a couple more filters. With Maidens min 10 starts. Because your system is Ratings based you maybe should consider a price based filter to salute the knowledge behind weight of money!
You've been down this track before with your D'S outsider system.

I just don't think Layers can ignore the use of many filters as our returns are always a fraction of liability, unless Laying Odds/On which was quite successful for me today.

I'm about to embark on a detailed survey of just Maiden races to try and find those profitable niches.

Cheers RP