I would be motivated by the following.

The Twins need to know if he can play defense adequately enough at the major league level. If not, they have no options for next year. He needs significant time this year.

They need to maximize his value in his prime ages of 26-30. Most players have a period of adjustment at this level. AAA and AA can not prepare them for major league pitchers. Reaching MLB 1000 PA's sometime during or before the age 26 season will maximize and lengthen their prime phase of their career. His lack of time at AAA will cause more growing pains, but by the end of next season we should know if he is a valuable piece to the team or not.

On another note, Casilla and Valencia have reached that threshold. They are in the midst of what would be their prime. This is the year they need to step forward or it is very likely we have seen the best they have to offer.