One of the most popular players in Brewers history, and affectionately known as "Stormin' Gorman", Thomas hit more home runs during the period 1978-1983 than any other player in the American League with 197. 

Gorman became an everyday center fielder for the Brewers in 1978 and clubbed 32 home runs to go along with 86 RBI. The next season (1979) Thomas enjoyed his best season in the Majors compiling career high numbers in home runs (45, tops 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). 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.

In 1982, Thomas hit an AL-high 39 home runs and drove in 112 runs to help the Brewers win the American League Championship and face the Cardinals in the World Series. Ultimately, the Brewers lost to the Cardinals in seven games. During the next season, he was involved in a trade that sent him to the Indians. He also played with the Mariners and returned to Milwaukee in 1986 for a last run.

Thomas was a career .225 hitter with 268 home runs and 782 RBI in 1435 games. An All-Star in 1981, he was considered for the MVP Award in 1979 (7th) and 1982 (8th). In 1982, Gorman was named an Outfielder on The Sporting News AL All-Star Team and also was selected as The Sporting News AL Comeback Player of the Year in 1985 as a member of the Seattle Mariners.

After his playing career finished, he worked for the Brewers to make appearances in the community and welcome visitors to Gorman's Grill at Miller Park. Thomas was elected to the Wisconsin Athletic Hall of Fame in 2003.