He played in Major League Baseball as an outfielder from 1969 through 1986, most notably as an integral member of the Cincinnati Reds, with whom he won two World Series championships, in 1975 and 1976.

A five-time All-Star, Foster was one of the most feared right-handed sluggers of his era, leading the National League in home runs twice (1977 and 1978), and in RBI three times (1976, 1977, and 1978).

[6] Foster returned to the Giants in September of the following year, hitting his first career home run off the San Diego Padres' Pat Dobson.

[7] He finally made an opening day roster in 1971 as a fourth outfielder behind Mays, Bobby Bonds and Ken Henderson, but shortly after the season started, Foster was traded to the Cincinnati Reds shortstop Frank Duffy and pitcher Vern Geishert on May 29.

[5] He returned to a back-up role in 1972, platooning in right field with César Gerónimo, and managed just a .200 batting average, two home runs and 12 RBI in 59 games.

[11] Foster spent the majority of the 1973 season with the Reds' Triple-A affiliate, the Indianapolis Indians, batting .262 with 15 home runs and 60 RBI in 134 games.

Tolan had suffered through a poor 1973 season in which he batted just .206, and was traded that winter to the San Diego Padres for pitcher Clay Kirby.

[5] Early in the 1975 season, Reds manager Sparky Anderson shifted perennial All-Star Pete Rose to third base, and used a platoon of Foster and Dan Driessen in left field.

The Reds won 108 games that year, tying the 1970 World Series champion Baltimore Orioles for the most regular season wins that decade.

The game was tied, and with the bases loaded and no outs in the ninth inning, reigning MVP and Rookie of the Year Fred Lynn lifted a ball down the left field line.

He turned in an MVP performance with a two-run home run and third RBI to pace his team to a 7–1 victory over the American League All-Stars.

[11] Foster turned in one of the all-time great seasons in 1977 on his way to winning the National League's Most Valuable Player Award.

[22] A home run the following day off the Houston Astros' Gene Pentz brought his season mark to 29 heading into the All-Star break.

[5] Foster picked up where he left off in 1978, with 18 home runs and 63 RBI in the first half of the season to earn his third consecutive All-Star start.

[31] Shortly after his return, the Reds went on an eight-game winning streak that saw them jump into first place by 1.5 games over the Houston Astros.

The Reds held off the Astros to win their first division crown since 1976, but were swept by the Pirates in the 1979 National League Championship Series.

At this point in his career, when it looked like he would one day rank among the game's all-time greats, Lawrence Ritter and Donald Honig included him in their book The 100 Greatest Baseball Players of All Time.

Unwilling to meet his contract demands,[35] the Reds traded him to the New York Mets for Greg Harris, Jim Kern and Alex Treviño on February 10, 1982.

On September 10, with the two teams tied atop the NL East, an incident between Foster and Cardinals pitcher Danny Cox caused both benches to clear.

The first game was a pitchers' duel between Ron Darling and John Tudor that the Mets won in extra innings.

He put up respectable power numbers (13 home runs and 38 RBIs), but had a .237 batting average, and had lost considerable range in left field.

[43] This game was highlighted by a bench-clearing brawl that was ignited when the Reds' Eric Davis stole third base in the tenth inning.

[47] In addition, Met teammates Wally Backman and Mookie Wilson have since said that Foster's non-combative personality was a bad fit for the team.

[48] On August 18, Foster signed a contract with the Chicago White Sox,[49] and hit the ground running with his new club.

[58][59][60][61] Foster was on the National Baseball Hall of Fame ballot for four years, having his highest total of 6.9% in 1993 before being dropped off after garnering 4.1% of the vote in 1995.