I feel the SR could be enhanced by trying to avoid races where outsiders are known to get up .

Those outsider races, are usually races where there are 12+ runners in a race.
So...
Maybe ones SR should be higher if one targets races where there are 11 runners & less.

The average SR for the top 2 in the market is approx 50% (30+20)

I dont know what the 3 percentage points difference makes , but it does appear to be logical.

The highest SR is 6 runners & less.

What also helps a lot is avoiding races where fields have first starters in them.
This tells us that there can be surprises in store for us.
So
Maybe only target fields where all horses have had 1+ career starts.

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Cheers.