How to counter Master Yi
Let us take a look on how to beat Master Yi. We will look at champions who are strong against Master Yi and who are weak against Master Yi. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Jungle champion who counters Master Yi. You can already win in champion select with the right counters for Master Yi. If you want to know how to counter Master Yi then you need to take into account the best picks vs Master Yi and the worst picks vs Master Yi. This Master Yi counter data is based on matches played by Pros on patch 15.1 and previous ones. It is important to see whether Pros counter picked Master Yi or whether they played as Master Yi.
Champions used by Pros to counter pick Master Yi
Looking at the matches from Pros (see table Pros counter picked Master Yi) we can see that they picked 
Lee Sin most often to counter pick Master Yi. The matchup Lee Sin vs Master Yi occured 15 times. Master Yi has 9 wins and 6 losses in this matchup. Learn how to counter pick Lee Sin to get another perspective on the data.
Lane outcome for Master Yi
When looking at Master Yi counters you will notice that win rates alone are not conclusional. Therefore we provide an overview (see table Lane Outcome) where you can see the lane outcome of Pros who played Master Yi. The lane outcome of Master Yi consists of three outcomes: Win, Loss or Draw. Let's take a look of Master Yi lane and match outcome for specific matchups. Considering the lane outcome and the match outcome of a specific matchup, might enable you to find the right counter for Master Yi.
Conclusion
Analyze the available data and learn how to beat Master Yi. To master Master Yi take also a look on Master Yi builds and runes for Master Yi. Good luck, Summoner!