After four plus seasons in their farm system, he was sent to the Boston Red Sox on June 30, 1972, as the player to be named later in the deal that brought future Cy Young Award winner Sparky Lyle to the Yankees in exchange for Danny Cater.

[1] Guerrero made the Red Sox out of spring training 1973, and won the starting shortstop job over Rick Burleson following Luis Aparicio's release.

He split 1975 between the Cardinals and their triple A affiliate, the Tulsa Oilers, batting .239 in 64 games at the major league level.

Guerrero signed as a free agent with the San Francisco Giants after the 1977 season, only to be sent to Oakland Athletics on April 7, 1978, to complete a trade in which the Athletics also acquired Gary Thomasson, Gary Alexander, Dave Heaverlo, John Henry Johnson, Phil Huffman, Alan Wirth and $300,000 for Vida Blue just over three weeks earlier on March 15.

[citation needed] While working as a buscón (headhunter) in the Dominican Republic, Guerrero sued Raúl Mondesí for 1% of his salary.