It is exactly what I think when I see them playing. Year after year you think that has to be it, Modric is too old, Benzema is too old, and then they perform like that. Vinicius Junior brings the spiciness into the game. Modric controls it and Benzema is a striker in its truest sense. I think Chelsea just isn't there yet, they haven't found and understood each other on the field.
Regarding Ancelotti, that is easier said than done!

You never know when you are at your peak. Zidane thought after his first Champions League title that he perhaps won't repeat it, and when he got the second he must have thought that a third can't be possible. Ancelotti sees his team showing these performances like against Liverpool and Barcelona, which coach in the world would say that's it, I have had enough?
There are not too old when looking Modric and Karim Benzema contribution for Real Madrid exactly last el clasico match when success eliminating Barcelona in semifinal Copa Del Rey. Look how effective with Luca Modric movement in midfielder area and success with beautiful assist for Karim Benzema scoring goals.
For Karim Benzema is most complicated as forward, he not only success with goals contribution but also he can play well with assists contributing for Vinicius Jr goals, Karim Benzema is not the typical selfish player and more priority with the other player if have good position or chance for scoring goals than push by him self how to score, become twice in a row Karim Benzema success with hattrick and waiting next match will consistent scoring goals again?