I used four seasons because thats what the original posters were discussing and I kept to that time frame. However its a good moment to consider his later career from anyway, because his career changes quite markedly after the 2018 world cup and he's never maintained how he was before then. He certainly was good pre-2018, no disagreement there, but there's only so far back you can look to predict future form. Looking back two or three seasons, sure, but if you're really trawling back 5 or 6 years to find evidence supporting a players, that kind of says it all.
He was not in fact voted the best keeper in the league in 2021-2022, that was
Alisson Becker. He hasn't been in the PFA team of the year since 2017-18. Since that time he's had one good season in terms of shot stopping, and even that was a game of two halves. In the second half of last season his shot stopping fell off a cliff and in the last 19 league games he was poor, conceding 2.2 more goals than the post shot-xG indicates (ie he conceded 2.2 goals more than even a bang average keeper would manage, never mind a good one). During that time he conceded more goals than the xG in 17 games.This season he's started, yet again, very average and is currently in 11th place on shot stopping.
His recent form shows him being very ordinary, and his mid-term form shows the same. Over his career, sure he's had plenty of great seasons, but that many years ago has little bearing on the present day. The good start to last season was both preceded and followed by consistently average form for longer periods. It would be wrong to try and pass that short spell off as the real picture of the player.
Not to mention the fact that this is only shot stopping we're talking about and he's incredibly weak in pretty much all other areas.