This is a spot where I think you have to take a step back from the analytics and look at the real, in game effect of a true impact guy in the lineup. With the rest of the lineup the Cubs are expected to run out next year that looks to have no real weak spot (assuming PCA and Amaya don't go back in the tank or another reliable C is signed), the impact of a 7 WAR guy whose value is primarily on offense will make a bigger impact on this lineup than going other routes. Having that guy who puts up a 178 OPS+ (career 160, which is probably more likely at Wrigley vs Yankee Stadium) as a constant threat in the lineup is going to have a bigger impact than a couple 125 OPS+ guys at the same price tag.