If it does end up costing him future earnings, it's on him. While he isn't unplayable at 2B, it's closer than it should be for any contending team. It isn't like Hiura is just going to throw away his infield glove, either. He's only 24 years old, and if he isn't traded, stands to be a part of this team much longer than Kolten Wong will likely be. He'll still see time at 2B, but not on a regular basis, unless Wong is injured. What this does, in essence, is give Hiura the chance to learn multiple other defensive positions, increasing his overall versatility, while giving him the opportunity to learn from the best defensive 2B in the game for at least the next two seasons. Wong is known as a great team guy, and I'm sure the Brewers see him as a mentor for Hiura.