Wallner's normal fielding allocation skills, are not at th e level of Gallo's normal fielding allocation, it is that simple.
For Wallner it is lef field, for Gallo it is 1st base; if they take either and stick them where it is new to them, no one expects either to do exceptionally well.
Wallner bats like Gallo, but without the above average fielding skill. (When Gallo played 3rd Base against the Twins, he did Very well there.