Well, my 2p in this one…
First of all some maps will always be in favor of the defending team simply because the map is too small.
And the one is teamwork, on main I’m sr6 on an good day but when backed up by an good shooting medic that does it job I’ll win any map regardless of the sr of the opponent. The keyword is teamwork, if that lacks in the (attacking) team ye doomed and the cry for shuffle becomes louder and louder. Noting more or less than that. Even I got shuffled because my team kept on winning map after map while based on k/d and sr we where an very low. No need for fancy shuffle addons just because the server got flawed maps in rotation or an team that has teamwork high on its agenda.
The above is the reason why I spec some maps as they are just not suited for our servers yet they are in high demand by the players.
Just team up and your unbeatable but remember to forget about k/d ratio cause that wil suck the big one when going for teamplay!