This actually happened on Friday night, but with the Paris attacks I've put writing about this on the backburner.
The Boston Red Sox acquired Craig Kimbrel from the San Diego Padres for four prospects.
Kimbrel will replace Koji Uehara as the team's closer. Uehara took over as closer in 2013 and was a key part of their World Series title run. Uehara saved 25 games for a mediocre Red Sox team in 2015, but his season ended in August with a broken wrist.
Despite Uehara's effectiveness, he is 40 while Kimbrel is 27.
Kimbrel began his career with the Atlanta Braves winning NL Rookie of the Year in 2011. He led the NL in saves every season between 2011-2014. On Opening Day, the Braves traded Kimbrel to the San Diego Padres. Kimbrel saved 39 games for a mediocre Padres team. He has 225 saves for his career.