Interesting. Would you mind sharing which metrics/formula you are using? I guess p/e and book value and others? Also do you use yahoo finance for the data?
Several industries do more commonly trade in a low p/e and book ratio close to 1, like banks, energy and shipping due to leverage and/or volatility in revenue.
in case you have the old scan data, an alternative way to testing the performance is by checking out the correlation between the script number and the yield after x-time. That will incorporate all of the stocks scanned and not only the selected few.