acquiring, by a bad change detector implemented by a processing device, metric data from a website while implementing a first version of an operational feature of the website and while implementing a second version of the operational feature;

detecting, by the bad change detector implemented by the processing device, a bad change to the website by measuring inequality among values of a frequency distribution defined by a time series of the metric data; and

reverting, by the bad change detector implemented by the processing device, the operational feature to the first version, automatically and without user intervention, in response to the detecting the bad change.