Let's say I've got a model which scores a trade set-up from 1 to 100 based on a number of objective factors. Any price action that triggers the set-up is a valid trade signal, but, historically, only trades which score above a 30 are profitable, in aggregate. Not that all trades under 30 fail, just that the profit factor is below 1. Taking only the trades above 30 yields a profit factor that is much higher and indicative of a robust strategy. Is ignoring any trade signal which scores below a 30 on the model "curve-fitting" or is it just a case of ignoring similar, yet somehow different, market action?