Nobody enjoys going up against the baseball skeptics. These people are notoriously averse to new ideas and philosophies. If it were up to them, everyone would be wearing stirrups.

But after several years of experimentation around the major leagues, even the purest of purists seem to have warmed up to one thoroughly modern tactic: the defensive shift. These days, more and more teams are positioning fielders in unusual locations based on the tendencies of the other team's hitters. The tactic has even been hailed as a low-cost...