"They get to the playoffs one year, and they think they are a great team, like the Yankees with Babe Ruth. We're just glad to be playing the Giants. We're just privileged to stand on the same blessed soil." — on facing his former team, the San Francisco Giants, as a member of the Cardinals, in the 1987 NL Championship Series

In his first 13 seasons, spent in the NL, this injury-prone slugger appeared in 140 or more games only three times. However, from the time he became a regular in 1977, he has had slugging percentages over .400 every year and five times has slugged better than .500, including a league-leading .597 in 1987. In '87 he led the NL in walks with 136 (while getting 120 hits) and HR percentage while hitting 35 HR with 106 RBI and 93 runs scored before an ankle injury ended his season on September 9. His inactivity probably cost him the MVP and the Cardinals the World Championship.

Clark missed most of 1986 with injuries after being the hero of the 1985 LCS with a dramatic ninth-inning three-run homer off Tom Niedenfuer in Game Six. Clark came to St. Louis prior to the 1985 season in exchange for David Green, Gary Rajsich, Dave LaPoint, and Jose Uribe; Clark had made clear his wish to escape both the Giants and Candlestick Park. In his nine years with San Francisco, Clark established himself as a superb clutch hitter, leading the NL in game-winning RBI (18) in 1980 and tying for the lead (21) in 1982. He led NL outfielders in assists in 1981, but was switched to first base to reduce the risk of injury.

After his career 1987 season, Clark got into a contract squabble with the Cardinals and signed as a free agent with the Yankees, who already had Don Mattingly at first base. He hit .242, his lowest average in a full season, and had 93 RBI, mostly as a DH. He escaped the "Bronx Zoo" to San Diego in return for Stan Jefferson, Lance McCullers, and Jimmy Jones in a blatant salary dump by management, but had his worst season in 1989.