Over his minor league career in the United States, López batted .316 with 511 hits, 72 doubles, 31 triples, and 39 home runs.

The California Angels purchased López from the Mexico City club from the Mexican League on December 3, 1973.

He started his career in the United States with the Double-A El Paso Diablos of the Texas League in 1974.

In 1975, López split the season with the Double-A El Paso Diablos and the Triple-A Salt Lake City Gulls.

López spent the 1976 season with the Triple-A Salt Lake City Gulls, and later made the California Angels' roster as a September call-up.

[4] At the age of 26, it was noted by The Associated Press that López and teammate Dick Pole were "the old men" on the Mariners' roster.

[5] The Associated Press also noted that fellow players and managers "rave" about López's speed, but also asserted that he had a throwing arm that was as good.

López was traded along with Tommy Moore from the Mariners to the Baltimore Orioles for Mike Parrott at the Winter Meetings on December 7, 1977.