This is impossible to quantify, mainly because the players have to win the game. Yost could have brought in Mota in the 12th, and Mota could have subsequently gone out and given up back-to-back homeruns. However, it is the manager's job to make sound decisions during the game. I would not be going too far out on a limb to say the majority of the 25,000 Brewer fans in attendance thought he was not doing his job in the 12th inning on 6/14. In the 11th Yost was sitting on a 16 with Tavarez, doubled down and got a 5. That doesn't mean you should do it again, ever. But to answer your question: the manager does not win games, so zero for me on that one. I would say Yost has cost the Brewers 2 wins so far this year (Rockies and Reds), while helping them to lose on several occasions.