I've mentioned this idea before. While Holliday learns the nuances of 2B this season, a future move (next year or two) to CF could make sense as well. Again, not this year. Ideally, EBJ will be our future CF, but not all prospects work out. If EBJ struggles to hit, having Holliday able to fill that spot as Mullins moves on could allow Westburg regular AB's at 2B, while filling an important defensive position in CF.
Versatility is important to the O's. Let him spend this season getting 2B down, but don't be surprised if during the Spring next season JH gets a few looks in center.