Kawasaki absolutely needs to be sent down, and it's the right baseball situation.
If Kawasaki weren't such a goofy, lovable guy, would you feel the same way about him?
The only thing he provides is a good approach at the plate. His defense is average and his hit tool is pathetic. But he takes a lot of pitches and spoils tough ones. There are a lot of guys in the minors that can do that.
If I had to choose between Kawasaki, Wagner and Perez, I'd choose the first option. Wagner is doing great and will contribute more than Kawasaki will. Perez would have to go on waivers and his performance so for guarantees he will be claimed.