Statistics experts: Can I increase total return by selecting from multiple systems when they are down?

[blue_prince_of_dallas]

I have created about 10 different systems which produce small returns trading forex.  The problem is that they have great variability.  Some days are very good, some days are very bad.  If a system has several bad days it seems to over perform in the following days.  If I switch between several systems on a daily basis removing the high performers and adding the low performers will total system return increase or is this like flipping a coin, the percentages never change, only the perception?