Adding Zobrist, Jaso and C. Young would immediately improve this team by 10 wins without looking at the pitching (assuming these players replace any combination of Gose/Castellanos/McCann/R. Davis for a large degree of games).
The pitchers suggested aren't world beaters and I personally wouldn't spend a dime on a reliever. But Tyler Ross + Latos/Fister are enough to fill in the starter gaps nicely.
All in all, if you don't spend on relievers, it allows to move forward without spend a great degree of money, except for maybe Zobrist. But I have liked Zobrist to be a Tiger for at least 5 years now.