Go look at what other teams are paying for their goalies, then. Spoiler alert: a ton of teams are paying $5 million for far worse results than Jarry gives. Of goalies making $4 million or more, all of Korpisalo, Knight (demoted to the AHL), Husso, Campbell, Petersen, Kuemper, Merzlikins, Grubauer and Gibson had worse years than Jarry last year. Hell, even Vasilevskiy had a worse year than Jarry last year.
Again, the reality is that goaltending in the NHL today is just ass so "consistently mediocre results" with Jarry is actually solid for goalie standards. It's not "Jarry is good", it's "NHL goaltending sucks so a goalie with Jarry's issues is still far better than what a lot of teams have".