Expected goals are relevant here. https://understat.com/league/EPL
Going by the difference of expected goals against to actual goals against, there's two teams being massively saved by their keepers this season - Burnley and United.
Taking the expected goals against as a measure for the quality of the defensive work of the team, United sit only fifth in the table.
Sounds about right. I have a feeling we'll be reminded of these statistics if/when Madrid eventually get their man.