Too lazy to find the posts again, but there was a lot of stuff here about his shot-saving stats being mediocre, barely positive, etc. I have no idea if this stat (PSxG-GA) is meaningful, but a comparison adds context.
Season | DDG | Ederson | Neuer | Mendy | Ramsdale | Lloris | Alisson | Sanchez | Meslier |
17-18 | +8.5 | -1.6 | -0.5 | - | | +0.6 | +10.8 | | |
18-19 | +0.1 | +4.1 | -5.5 | +4.4 | | +10.2 | +5.9 | | |
19-20 | +2.1 | +2.5 | +2.5 | +1.9 | -0.4 | +7.3 | +0.6 | | |
20-21 | +0.1 | +2.2 | +2.2 | +0.1 | +1.9 | +5 | +5.9 | +4.8 | +5.3 |
21-22 | +6.7 | -1.2 | -1.2 | -0.4 | -4.3 | -0.5 | +4.4 | +1.2 | -7.3 |
22-23 | +0.1 | -0.6 | +1.2 | -1.9 | -1.6 | -1.4 | +0.1 | +2.6 | -1.4 |
Avg/90 | +0.10 | +0.03 | -0.01 | +0.03 | -0.04 | +0.12 | +0.16 | +0.12 | -0.04 |
(tldr - Alisson is a freak, DDG is comfortably in the tier below, Sanchez could be a steady replacement, run away from Meslier)
Also, keeping in mind that this includes his bad form of 18-19 and slow decline since, I'd guess that his peak years (2013-18) would have insane numbers, probably consecutive seasons +5 or more. Sadly this stat isn't measured before 2018.