I am trying to use glicko 2 rating system in my game. I have implemented it using the formulas described in the document. However I am not sure I understand correctly how the rating deviation φ of a player is increased after periods of inactivity. The document mentions that when a player does not compete during a "rating period" the deviation φ is updated using this formula:
φ = sqrt(φ^2 + σ^2) (could not embed the formula, it seems that image extensions has been disabled)
where σ is rating volatility.
But using that formula it seems that φ is increased in a very slow rate. For example if a "rating period" is one month and a player has φ = 50 and σ = 0.06(the recommended value for volatility), after 10 years(120 "rating periods") of inactivity φ' = 50.004189. Is that the expected behavior or I am missing something? Is there any way to adjust how "quickly" φ is increased during player inactivity?
Let's hope that there is someone that has used this algorithm in the forums.
Thanks in advance!