I have not used Streak so I cant comment on that but I wanted to tell you this.
You take a coin. Flip it a million times. In the end you will find that the result is roughly 50:50. So in your test you are doing the same thing. There are only two outcomes here. So it has to be 50% probability.
There cannot be one single algo working well across all stocks. Its not possible. It will work only if it is flexible/adaptable/morphs to different situations. And that is not possible with Streak.