This season (excl. his last EPL appearance against Burnley), it's 20.2 (xG) vs 23 (conceded).
For Sunderland: xG 135.4, conceded 117
For Liverpool: xG 162.5, conceded 179
So in the table you posted before, he would have an "xG prevented" score of -2.8, placing his 2nd worst among the top-6 GKs after Cech. Sounds about right.