Overall Santos has been comfortably our best player during preseason IMO. Mount was up there with him (perhaps even slightly ahead) for the first three games, but then against PSG he had the poor start and injury.
I think Santos did have a quiet period in the middle of the first half of this match though, as well as for the 20 minutes he played in the second half against PSG. Both times were when the opposition were getting on top for a while, so I'm hoping that's not a trend. When the opposition is getting on top is almost when you need your DM to be most involved. Just something I'll be watching in the future. Other than that though he's been great.
Somebody above compared him to Carrick, and yeah there's definitely similarities on the ball. Carrick in the latter part of his career anyway; in his earlier days he tended to play second-fiddle to Scholes when it came to moving the ball forward. Santos hasn't quite shown the longer-range passes that Carrick could make though, so it'll be interesting to see if that will come.