There are two issues I have with this: First, there is a "best ban" and your team must use distinct bans, meaning there are five "best bans." So while your model may say that Samira should be banned in 30% of games, she in fact should be banned in every game if players are banning optimally.
According to Lolalytics, the 5 best (play rate * win rate) bans in patch 10.21 are Samira, Zed, Jhin, Hecarim, and Lulu.
So seeing Samira and Zed in your list as disproportionately banned, despite being the two best bans in League of Legends (and, almost more importantly, the #1 Bot Lane and #1 Mid Lane bans), makes this methodology feel flawed.
The second issue is that sub-50% win rates are champions you want to see in your games because you're likely to beat them. This is why it feels odd that Jhin and Ezreal are next to each other. Jhin is indeed left up more often than his power level suggests. However, Ezreal shouldn't be banned: He doesn't win very often a...
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