Change the default graph to Elo Estimate from self-elo.

[MaurizioDeLeo]

The amount of questions on the discord and in other forums regarding self-elo is still very high.
I would say that questions on why self-elo is going down may be the first cause of frustration and loss of contribution for new users.

A simple change of the default graph to "elo estimates" would solve a lot of these issues.