Every mid-year trade-deadline period is different. But the last few years, each has had its defining elements. In 2015, the eventual World Series opponents both traded for key bats. The Royals got Ben Zobrist, and the Mets landed Yoenis Cespedes.
In 2016, the Cubs and Indians outbid the field for the best available relievers in Aroldis Chapman and Andrew Miller. And last year, the Astros and Dodgers nabbed the two best starting pitchers in Justin Verlander and Yu Darvish. In fact, the Astros probably don’t make the World Series without Verlander. If the Dodgers had acquired Verlander instead, they probably reign now as defending champions instead of Game 7 runners up.