What pre-patch means on a row

If a brawler gets changed, we don't mix the old and new numbers together. For that brawler, the analysis uses the battles from before the change until there are enough battles after the patch to make the new data more reliable.

Nothing gets removed. The old data simply stays in use for a while and is replaced once the post-patch sample catches up. This can happen at different times for different rows, depending on how often that brawler or map is played.

The patch day itself isn't counted as a clean break, since battles from before and after the update are still grouped together. The earliest a row can switch to the new data is therefore the following day.

For overall win rate this usually happens fairly quickly. Individual maps can take longer if they aren't played as often.