Not directly wrong, but a bit oversimplified explanation which enda up in the wrong conclusion in my view.
One situation was, unless I’m confusing situations, Mbeumo completely brainfarting the reception of a perfectly good pass, giving a counter-counter situation that ended up in a corner kick. If we suddenly are viewing ‘conceding a corner kick’ as ‘giving up a goal chance’, it says more about our vulnerability on set pieces, which is what should be dealt with. Regardless, Santos did nothing wrong there, and replacing him with Baleba or Sangare would have added nothing.
Second situation was Tielemans, actually untypical of him but probably typical of a player new to a team, was in the wrong position for defending the box, had to sprint out and therefore was passed too easily and conceded a free kick. Stas will tell you that a freekick from that position is not a very potent chance, even if they may result in a goal from time to time given how frequent they are. Ideally we don’t give them away, though. Regarding my post, which was about having Baleba for this game wouldn’t have changed much, or perhaps even negatively, I think it’s fairly obvious that Baleba is not an alternative to Tielemans, and certainly not against the likes of Hull. Rather, he is a player who even more allows us to play Tielemans. And even if Baleba was playing on the right sided CM position there, the chances of him positioning himself too low on occasion during his first minutes for United would be at least as likely as Tielemans doing so. Either way again, we’ll concede some free kicks regularily in those positions, we can’t expect to let in goals from them. That’s a set piece defending problem, not a midfield defending problem.