In February 1978, O'Brien sold Thomas back to Milwaukee before he appeared in any games with the Rangers. Becoming an everyday center fielder for the Brewers in 1978, Thomas hit 32 home runs to go along with 86 RBI. In 1979, Thomas enjoyed his best MLB season, compiling career high numbers in home runs (45, first in the AL), RBI (123), runs scored (97), hits (136), doubles (29), walks (98), on-base percentage (.356), total bases (300), slugging percentage (.539) and OPS (.895). He finished seventh in MVP Award voting. Thomas was affectionately known as "Stormin' Gorman." In 1980, Thomas had another productive season, hitting 38 home runs to go along with 105 RBI, while playing in every game. Gorman followed that up in 1981 by finishing second in the AL in home runs with 21 and being named to the AL All-Star Team. He finished eighth in MVP Award voting that year. In 1982, Thomas hit an AL-high 39 home runs (tying with Reggie Jackson for the league lead) and drove in 112 runs to help the Brewers win the American League Championship and face the Cardinals in the World Series. The Brewers lost to the Cardinals in seven games, with Thomas striking out against Bruce Sutter to end the Series. While with the Brewers, Thomas opened a bar in Milwaukee with pitcher Pete Vuckovich. It was called "Stormin' & Vuke's", a play on their nicknames. In June 1983, Thomas, Jamie Easterly, and Ernie Camacho were traded to the Cleveland Indians in exchange for Rick Manning and Rick Waits. Thomas's play had declined late in the 1982 season; he hit .181 after September 1, and he had only four hits in more than 40 at bats in the 1982 postseason. After the announcement of the trade, angry Brewers fans flooded the team's switchboard with phone calls criticizing the transaction. After the 1983 season, Thomas expressed his desire for another trade, saying that he did not feel comfortable playing in Cleveland. Thomas had hit more home runs during the period from 1978 to 1983 than any other player in the AL (197). Traded to the Seattle Mariners for the 1984 season, Thomas played in only 53 games for the team that year before he underwent season-ending rotator cuff surgery in June. In spring training before the 1985 season, Thomas had some difficulty with the timing of his swing, but he was able to swing without pain and he was looking forward to assuming Seattle's designated hitter role.