Ryu was a 2.5 fWAR pitcher last year. He started 31 games. If he's not on the team they are mathematically eliminated a couple of days earlier.
The Ryan comp misses a bit. One good year on a five year deal is obviously worse than whatever the end result ends up being with Ryu. Even if Ryu limps to the finish with 1 WAR this year and next, he is a way better outcome than Ryan.