Excellent stuff, agree with alot you said, and I went over my figures and your comments backed up my figures.

ie. backfitting a high strike rate system
Place to winners ratio - 0.625.
I smell a rat here, maybe this is why I have had many 2nds and 3rds this month, I probably over-filtered to achieve the historical profit.
It is all levelling out, profit turnover still good though, but going down slightly over time.
Needs many more bets in system yet.

ie. backfitting a longshot system
Place to winners ratio - 1.219
This looks on the money, plenty of 2nds, but the profit is still over 50% after 170 bets on the win only. Which indicates to me it has probably been through a slighty bad run, and looking at Feb results. 6 bets, 3 wins and a 3rd so the place ratio is moving slighty back towards 1:1 and the profit is climbing up over 55% now. Will still need another 100-200 bets at least for me though.

Exactly the comments I was looking for, thanks, and I'll now be careful backfitting a system if the new results don't show a place to winners ratio of at least 0.80:1, ideally 1.20:1 with a system showing strong win profits is a great sign that you are on the right path.

Any system (even backfitted, even if it sucks) after roughly 500 or so bets should hopefully have this kind of ratio anyway. It was something I began to think about yesterday when I couldn't work out why every system I backfit begins to fail, this may be the answer. I over filtered to achieve the historical profit and I just kept the winners having a good run mostly, now they are beginning to come 2nd and 3rd.
Murphy's Law hey?

Cheers,