It’s just logic. There are three “filters”, if you will, regulating who stays in GM and who drops out.
- Players want to win, so they play the best heroes and climb to or stay in GM.
- Players want to play [hero that just so happens to be good], so they climb to or stay in GM.
- Players want to play [hero that just so happens to be bad], so they do not climb to or fall out of GM.
Thus, the population in GM will be reflective of what heroes are viable and optimal.
There hasn’t really been a time where Lucio was bad. He’s been Meta more often than just about any other hero in the game, so this fits under the second “filter”.
I didn’t mean that as an absolute. Of course the “meta” characters are not going to have 16.67% GM pickrates while everyone else has 0%. You can certainly one-trick sub-optimal characters to GM if you put the time and effort in; I did so with Mercy back when she was hands-down the worst healer in the game prior to her rework. What matters is how difficult it is to reach and maintain GM with that given hero. The easier it is to reach GM as a certain hero, the higher that hero’s pickrate will be in GM. The harder it is to reach GM as a certain hero, the lower that hero’s pickrate will be in GM.
Of course, when working with a data set as large as this one, there are bound to be some outliers, but that doesn’t take away from the overall trends that can be observed from pickrates.
As an example, in season 4, Mercy had a 12% Quickplay pickrate (the highest in the game) and a 13% overall Competitive Play pickrate (also the highest in the game). Yet, when you sorted for GM, her pickrate was dead last of all healers at 3-4%. That’s because GM weeds out the influence raw popularity has over pickrates. Again, there were outliers; there were still Mercy players in GM, but every hero will see at least some playtime in every rank, regardless as to how bad they are in regards to viability.
…Except for Bastion. Fun fact: Bastion is the only character in the game to ever maintain a 0% pickrate in GM for a month.