2012 Boston Red Sox into 2013 season
2012 record: 69-93 (5th in American League East)
2013 record: 97-65 (1st in American League East, won the World Series against the St. Louis Cardinals)
This rags-to-riches story is one of the most successful retools in the history of baseball. The Red Sox won 90 games in 2011, but they missed the playoffs that year. Their 2012 season was abysmal; Terry Francona had just departed before the 2012 season, and Bobby Valentine led an uninspired group of players to a terrible season.
The subsequent offseason included the Red Sox firing Bobby Valentine and hiring John Farrell as his replacement. They signed catcher David Ross, outfielder Shane Victorino, pitcher Koji Uehara, Stephen Drew, Joel Hanrahan, and outfielder Jonny Gomes over the offseason to fill crucial holes on the roster. They also traded for catcher/first baseman Mike Napoli.
In just one offseason of acquisitions, the Red Sox remade their roster. In total, they spent well over $60 million in free agency. They were able to spend this money thanks to wily trades by Ben Cherington during the season. Cherington traded away Adrian Gonzales, Carl Crawford, and Josh Becket to the Los Angeles Dodgers, putting the BoSox under the luxury tax threshold.
Thanks to trades that involved offloading of over-priced stars and careful spending in the offseason, the Red Sox were able to turn a sub-70-win team into a World Series Champion in just one season. The Cardinals could mirror this methodology this trade deadline and offseason. By being willing to trade expensive stars like Sonny Gray, Nolan Arenado, and Willson Contreras, the Cardinals could open up financial flexibility to spend via free agency.