Sacy is fluent, he only remarked that IGLing would be difficult to do in English, and he never did it for Sentinels. Pancada might have struggled in the first months, but now he speaks well enough to be compared to Alfajer, yet their performance difference is still abysmal. Roles were the issue, of course, but this team has no cohesion at all.
They just put these players together, and they probably have very different styles and mindsets. Imagine the former LOUD players getting Depph as the IGL when they had Saadhak, then they went to Marved, who was completely new to the role. Also, until the team's struggles bring them together, they probably had nothing to aim for as a team, and perhaps not even TenZ care anymore about Sentinels not getting trophies as an org. There was no glue, and even now this is their main issue.
Their plans for the next season are good, finally they have a proper IGL, and Zellsis performed well even when he was lost in the first map (they never practiced Sunset with him, John said). They reversed a loss, which is a good start, and it's the first win without Zekken carrying. Still, the team's synergy is lacking, if they want to go to Masters and beyond, they need to improve their teamwork and figure out something to aim for together.