The Chicago Cubs acquired closer Aroldis Chapman, the hardest thrower in baseball history and the back-end bullpen piece they’ve coveted as they try to win their first World Series in more than a century, for a package of prospects sent to the New York Yankees on Monday, sources familiar with the deal told Yahoo Sports.

The 28-year-old Chapman, who this week hit a record 105.1 mph with his fastball one game and another repeatedly threw harder than 104 mph, was coveted by teams across baseball after a half-decade as one of the game’s best closers. The Cubs especially desired Chapman, and they gave up arguably their top prospect, shortstop Gleyber Torres, as part of the deal to get him, in addition to RHP Adam Warren, OF Billy McKinney, and OF Rashad Crawford.

With the trade, the Cubs cemented themselves as the team to beat going into October. Chapman will join a newly revamped bullpen that includes left-hander Mike Montgomery, whom Chicago acquired last week, along with incumbent closer Hector Rondon, setup man Pedro Strop and standout rookie Carl Edwards Jr.

The price for Torres, who some believe will end up at second base, is nonetheless steep, particularly considering the Yankees acquired Chapman at a bargain-basement cost over the winter following a domestic incident for which he served a month-long suspension. Chapman, who will be a free agent this offseason, came back looking as good as ever, and the trade market was far more robust, with the Washington Nationals and Cleveland Indians making strong runs before the Yankees agree to the deal with Chicago.

In 31 1/3 innings this season, Chapman has struck out 44 and walked eight, a career-best walk rate. Torres, 19, is one of the youngest players at High-A and has more than acquitted himself with a .275/.359/.433 line.

The Cubs, whose 59-38 record is the best in baseball, could stand pat as the rest of baseball grinds toward the Aug. 1 trade deadline. The Yankees, in the meantime, could just be getting started. They’ll now turn to finding a possible destination for sought-after reliever Andrew Miller as well as consider dealing from their cache of back-end starting pitchers.