This tool highlights the most overpowered heroes in the current pub meta. It simply compares the win rates (for each skill level) from each part of the game (early, mid and late).
The standard deviation (σ) column is a measurement of how different the win rates are between skill levels.
Raw data from all pick matches is taken into consideration. This means that picking these heroes does not guarantee a win, they may have better win rates only because they were picked in certain lineups.
The data is taken from the picker so it updates frequently.