I think as a group of fans we're so used to blaming the midfield to the point that with any bad result, we automatically blame them. Neither Santos nor Tielemans are physical beasts, but they controlled the centre of the pitch without much fuss, even with Tielemans clearly unfit (probably a bit more to do with Hull letting us have it).
Apart from that comical McMessi moment, we didn't get carved open through the middle with transitions as we've had to suffer in the past, we were not overrun at any point, they both had a very high number of passes and a very high pass percentage, ending with us having 71% possession or something wild. Now I'm not saying they were great by the way, but the job was done in midfield.
Granted, they're not Casemiro-level monsters in both boxes, but not many are, as that's not a midfielder's primary job. We got done by set pieces, and other than that, all the Hull City threat came from the wide positions. We also had to deal with a reshuffled, dysfunctional forward line which offered no threat.
Santos, from what I've seen, is not an all action player. He takes good defensive positions, blocking spaces in midfield, and plays a simple but very effective game which is easy to overlook or even deride when we have poor games - a bit like his manager.