Great topic - Every Topic (forgive the pun).

The downfall of many a system is, as you say, not finding the winners, but eliminating the losers and the races which are not good betting.

Often with a very firm, even odds on favourite in a field, the price of the "outsiders" is way over what it should be.
One thing I have done in the past is to do the form without the odds on pop included to see just how far over the odds your choice would have been if the hotpot wasn't there.

Now, the problem here is that the odds on pop is often odds on for a reason, but from a value angle, your outsider might be a better bet.

The actual result has to be seen not from the one race but in longterm view.

So I would include the outsider in odds on fields or small fields, as sometimes there is great value, as the horse is not a "bolter" but actually has a realistic chance of winning.

Never overlook the fact that the horse, dog, trotter or fly with the best form and class doesn't always win. Bad luck in running should never be underestimated.

In other words, "If the odds on pop gets a bump, a check, gets trapped wide, is my outsider hopeless or has it a real chance?"

I'll have some systems to provide to this topic later.