I feel like they lack composure and awareness when they lose maps or rounds. When this years SEN are at their best is when they make quick and decisive calls and execute it calmly, they look horrible when they commit to bad call and rush. For example, SEN lost like 10 rounds this series up a man advantage on attack and they get too excited and stomp away to one site to group up and G2 make a hero stack play to win the round. Honestly, those 10 rounds were difference maker in this series.
Also, their defensive setups are too readable, they are not rotating or flooding as much as they should, they are not proactive enough.