I think we were 'figured out' after 17/18. Even in Sterling's best season for us, 18/19, we'd steered away from our wingers using their pace shown by the fact even Sane wasn't first choice anymore.
Sterling was just a lot more effective at cutting in and shooting that year than he has been since. He seemed to play with clarity rather than being confused every time he got the ball as has become pretty common with him.
The less of the ball he sees, the better he is purely because his movement (and pace to get there) is next level. Chelsea's style is perfect for him and he'll thrive there but I personally just think we may have outgrown him and his strengths.
And even if he's not particularly using his pace every second of every game, he's used it effectively when it's needed (vs Villa) and the choice is there too if needed. We'll suffer massively if we haven't got somebody who can attack with pace if he's not replaced.