Not sure what you have watched...
Biss was brilliant for first 7 rounds and either dogshit or straight out missing in next 14. So twice the time he has been good, he has been nothing. Not press resistant, not mobile, not reliable.
Bentancur is much more aware on the ball than Bissouma, defensively he can do the job as well. Mobility and agility - from what Ive seen in recent games is better than most Bissouma performances.
Bentancur had arguably as good as any #6 performance as Bissouma in the first games, coming straight from 10 month absence, until that cunt Cash took him out.
Also, that is getting too detailed, but red card was absolutely right call, you have to be biased as hell if you put Calvert-Lewin and Bissouma situations to "similar" situations. He first fucked up under pressure (khm...press resistance) and then to make it up, totally lost his mind and went in studs up.
I am not writing him off, but what I am saying is simple - Bissouma has been shocking in recent times and it is his job to fight back his place in starting XI. For that he has to cut out A LOT what he has been doing. We need first-7-rounds-Bissouma back to be flying, but it is down to him to prove it was not a fluke.