...If you were to track an entire season in this manner, you would have a Win Contribution metric that is more accurate than Win Shares, because it is based on how much each event actually contributed to the team's wins. In a way, WPA is the ultimate baseball statistic. And in a way, it is not.
Like Win Shares, WPA is not a good predictive statistic because it's not necessarily a good representation of a player's true talent. If a player hits a home run in the ninth inning of a 1-0 game, he is credited with more WPA points than if he hits a home run in the first inning of a 1-0 game. The talent is the ability to hit the home run; when it happens in a game is something that is pretty random. When you are thinking of acquiring a player for your fantasy team, you should rely more on the traditional sabermetric stats, like Linear Weights, Runs Created, DIPS, etc. etc....