What makes an "S+" Run? I just got #76 on Revelations with a score of like 340something thousand points with an S rank and an on-beat percentage of 97+ and an accuracy percentage of 99.1%.

Meanwhile the guy about 3 ranks below me (who had a cloudhead logo next to his name, is he a dev or something?) had an accuracy and onbeat rating lower than me, a lower score than me, and no modifiers same as me however he got S+. Any idea how this works?