CHICAGO - The Chicago Cubs already boasted one of the best young cores in baseball — and that was before they added one of the top outfielders.

Free agent Jason Heyward agreed to a $184 million, eight-year contract with the Cubs, according to a person familiar with the negotiations.

The person spoke Friday on the condition of anonymity because the deal has not been announced.

The agreement with the three-time Gold Glove winner is the latest in a series of big moves by the Cubs as they try to build on a breakthrough season and bring home their first World Series title since 1908. The Cubs won 97 games and reached the NL Championship Series before getting swept by the New York Mets.

Chicago also has added pitchers John Lackey and Adam Warren along with infielder Ben Zobrist. Lackey, like Heyward, left the rival Cardinals for the Cubs and figures to be Chicago's No. 3 starter behind NL Cy Young Award winner Jake Arrieta and Jon Lester.

An All-Star in 2010, the 26-year-old Heyward hit .293 with 13 homers and 60 RBIs this year, helping St. Louis win the NL Central. He spent his first five big league seasons with Atlanta.

Chicago also signed Zobrist to a $56 million, four-year contract and traded Starlin Castro to the New York Yankees for Warren.

Heyward has a .268 career batting average and has hit more than 18 home runs just once. But the Cubs are counting on him to help strengthen a batting order that includes young sluggers Anthony Rizzo, Kris Bryant and Kyle Schwarber along with Addison Russell. All are 26 or younger, with Rizzo a two-time All-Star and Bryant a unanimous pick for NL Rookie of the Year.

The Cubs also are counting on Heyward to help solidify their outfield, whether they keep him in right field or move him to centre. If Heyward plays right, they could try to trade Jorge Soler for a pitcher or centre fielder.

The addition of Heyward will only further fuel expectations after the Cubs finished with both the third-best record in the majors and in their division. Even though they took two players from the Cardinals, beating St. Louis and Pittsburgh in the Central won't be easy.

Still the moves they made reinforce just how serious the Cubs are about winning their first pennant since 1945. They won their last title 17 days after the Ford's first Model T left the car factory in 1908.

Chairman Tom Ricketts was willing to open up the checkbook rather than wait for more revenue from the Wrigley Field renovation and potential TV deal to kick in.

While the Cubs might wind up having overpaid for Zobrist, who turns 35 in May, on the back end of his contract, Heyward should have plenty of prime seasons remaining. That's a big difference from the $136 million, eight-year deal the Cubs gave Alfonso Soriano under previous ownership and management before the 2007 season. Soriano was 31 at the time, and while he helped Chicago win division titles the first two seasons, his deal became a burden as he started to decline.