Pulisic being on the bench had to be expected as he is consistently stronger as sub than as starter. I can´t really pinpoint it but something about his game gives his opposing players tremendous trouble for a time until they adapt to it. Pulisic as of right now is an ideal player for half an hour, probably our strongest high impact sub.
Dembele on the bench pretty much means to me, that Reus is not expected to play the full game (he might have an hour or so in his tank) and Tuchel wants exchange on the highest level later against tired opposition.
The whole game rides on our ability to score early. If we do so we rip the tie wide open.
I guess that makes sense, let's see how it plays out.