Lou Brock, 81, was always a threat on the bases

Lou Brock, the Hall of Fame outfielder who became the greatest base-stealer the major leagues had ever known when he eclipsed the single-season and career records for steals in a career spanning two decades, died Sunday. He was 81.

Dick Zitzmann, Brock's agent, confirmed his death to the Associated Press, but did not provide any details. In 2017, Brock began receiving treatment for multiple myeloma, a type of blood cancer. The Cardinals and Cubs observed a moment of silence in Brock's memory before their game at Wrigley Field.

"Lou Brock was one of the most revered members of the St. Louis Cardinals organization and one of the very best to ever wear the Birds on the Bat," Cardinals Bill DeWitt Jr. said in a release. "He will be deeply missed and forever remembered."

On June 15, 1964, a floundering St. Louis Cardinals team traded one of the National League's leading pitchers for an outfielder who had failed to live up to his promise. That deal, sending the righthander Ernie Broglio to the Chicago Cubs for Brock as the centerpiece of a six-player swap, became one of the most one-sided trades in baseball history, but hardly in the way that many envisioned.

"I thought it was a dumb trade," Cardinals pitcher Bob Gibson told the St. Louis Post-Dispatch. "I didn't know how good Lou would be. No one knew."

Brock, sought by Cardinals manager Johnny Keane for his largely untapped speed, helped take St. Louis to the 1964 World Series championship and went on to turn around games year after year with his feet and bat.

Brock's 118 stolen bases in 1974 eclipsed Maury Wills' single-season record of 104, set in 1962, and his 938 career steals broke Ty Cobb's mark of 893.

He led the NL in steals eight times. Although Rickey Henderson broke Brock's stolen base records, Brock's luster remained undimmed. A lefthanded batter, he had 3,023 hits and he hit .300 eight times. He helped propel the Cardinals to three pennants and two World Series championships — batting .391 with four homers, 16 RBI and 14 steals in 21 World Series games — and was elected to the Baseball Hall of Fame in 1985.

Brock's death came after Hall of Fame pitcher Tom Seaver died Monday. Brock and Seaver faced each other 157 times, the most prolific matchup for both of them in their careers.