Yes, I have an explanation. There is an almost 100% accurate rule when dealing with advisory services: If an advisory service has a wonderful track record up until you start using them, as soon as you start following their advice they will lose their golden touch.
This is due to “survivor bias”; that is, even if every advisory service used random numbers to make their predictions, if there are enough services, one or more of them will have an excellent track record, viewed retrospectively. Unfortunately, that doesn’t mean that their track record will continue in the future, for obvious reasons.