Well he displaced Nani after Nani had one of his best seasons for United both with goals and assists, so he was obviously fairly efficient otherwise he wouldn't have become United's first choice right midfielder.
Liverpool broke through with the pace of Salah a few times yes, but they actually ended up creating few goal scoring chances from it, partially down to their efforts and partially down to City's defending. Salah broke through for example after skinning Otamendi and tamely placed a shot at the keeper, but was forced to take the shot rather than square it to Firminho because Stones had blocked the angle for a pass.
When City were caught on the break high up the pitch, there may have been acres of space for Liverpool to run into but generally the back four+ were structured quite well which prevented Salah bringing anyone else into play.
There was only one real chance from those breaks from Salah and Ederson dealt with that pretty easily.