Well football is not a 1-0-1-0 binary game that is based on data. Sometimes players work really hard, like seriously hard in a game, and the other team doesn't play that well, we are all humans and we have bad days and it happens, you can't expect 100% from every player every game. That is exactly what happened with Sheriff, they played very very hard (not meaning tackles, just running around a lot) and they gave it their all because they know this could be one of the rare chances they could be in the groups so they wanted to show themselves, and maybe some of them would be bought by bigger clubs and paid decent wages.
So, it is about "heart" and sheriff put up a lot more heart. They also look like they might actually end up going to next stage as well, they already have 6 points and if they end up losing every single game left then they might end up not going to next stage but if they get some draws and maybe another win then they could actually be going further.
it's not a data-driven game, it's true
but the data, historical data, series of the last games .. give you an indication on the most probable result
which is not carved in stone, can be (and this happens) overturned
this is why it is so exciting as a sport, because there are cases in which a small and not really strong team wins (put your luck in it too)