The horizontal axis shows the go rating scale used by the EGD and the revised rating system.
The vertical axis shows units of log-odds per rating point.
The thick blue line is 1/a in a standard Elo rating system.
The colored lines from yellow to blue are log-odds / delta, colored per rating grade.
The green line corresponds to 1/a (the limit for delta equals 0).
To reduce clutter, I projected positive delta to the left and negative delta to the right of the green line.