First of all I'd defeinitely sign a 26 year old Yelich for 5/110 if he were a free agent.
I think you're looking at Chen's contract wrong. There is a lot of deffered money in there. It would cost us $52M over the next 4 years not counting the 2021 option. I also think he's good for at least 3 WAR over the next 3 seasons so I'd put the sunk cost at about $30M