It doesn't make sense to me. Yamamoto can't put a puck in a lake. Kostin is bigger, more physical, can fight and has twice the goals.
Historically so far Yamamoto is a better goal scorer. Kostin scored 4 goals last year and Yamamoto had 20. There has to be something up with Kostin injury wise though.
We should also prob give Yamamoto a break because he's been in and out of the lineup