Those stats should be taken with a pinch of salt, sure we conceded 54 goals the season before Maguire arrived but that was a disaster season where players had totally lowered their guns for Mourinho. Before that season we had conceded 28 goals in the 2017/18, 29 goals in the 2016/2017, 35 goals in the 2015/2016.
For reference this season we have already conceded 32, at this pace we'll finish with 42.
So let's not pretend that buying Maguire made us a defensive force or anything, taking Mourinho's last season as level ground is biased to say the least.