Thomas became one of baseball's biggest stars in the 1990s, playing for the Chicago White Sox. He was given the nickname "The Big Hurt" by broadcaster Ken Harrelson, who coined the term in the 1992 season. Frank Thomas is known, not only for his menacing home run power, but also for striking fear in the competition by swinging a rusted iron pipe (reportedly found during a renovation project in Old Comiskey Park) in the on-deck circle.
Thomas is one of several notable baseball players who played college baseball at Auburn University, such as Bo Jackson, who was also a teammate of Thomas in the major leagues. He also played tight end for the school's football team. Thomas has hit over 500 career home runs, thus making him a strong candidate for the Baseball Hall of Fame when eligible. Thomas is part of an elite group as one of only four players in baseball history to have at least a .300 average, 500 home runs, 1,500 RBIs, 1,000 runs and 1,500 walks in a career. The others are Mel Ott, Babe Ruth and Ted Williams.
"I was shocked and sad," Thomas recalled in the Chicago Tribune. "I saw a lot of guys I played against get drafted, and I knew they couldn't do what I could do. But I've had people all my life saying you can't do this, you can't do that. It scars you. No matter how well I've done. People have misunderstood me for some reason. I was always one of the most competitive kids around."
In the autumn of 1986, Thomas accepted a scholarship to play football at Auburn University. Even so, his love of baseball drew him to the Auburn baseball team, where the coach immediately recognized his potential. "We loved him," Auburn baseball coach Hal Baird told Sports Illustrated. "He was fun to be around—always smiling, always bright-eyed." He was also a deadly hitter, posting a .359 batting average and leading the Tigers in runs batted in as a freshman. During the summer of 1987 he played for the U.S. Pan American Team, earning a spot on the final roster that would compete in the Pan American Games. The Games coincided with the beginning of football practice back at Auburn, so he left the Pan Am team and returned to college—only to be injured twice in early season football games.
Thomas might have lost his scholarship that year because he could no longer play football. Instead Auburn continued his funding, and baseball became his sole sport. He was good enough as a sophomore to win consideration for the U.S. National Team—preparing for the 1988 Summer Olympics—but he was cut from the final squad. Stung and misunderstood again, he fought back. By the end of his junior baseball season he had hit 19 home runs, 19 doubles, and had batted .403 with a slugging percentage of .801. With another amateur draft looming, the scouts began to comprehend that the big Georgia native could indeed play baseball. By his senior year (1989) he was voted the Southeastern Conference MVP in baseball, leaving the school with forty-nine career homers, a school record.
The Chicago White Sox selected Thomas seventh in the first round of the June 1989 draft. Thomas played first base during the early part of his career and was not known for his defense. He never won a Gold Glove at the position, and has played primarily as a designated hitter since turning 30 years old. Rather, Thomas is known for his offensive performance; some regard him as one of the best pure hitters in baseball's history. Thomas is the only player in major league history to have seven consecutive seasons of a .300 average, and at least 100 walks, 100 runs, 100 runs batted in, and 20 home runs (from 1991 to 1997). The only other player to have more than five consecutive seasons accomplishing this feat was Ted Williams with six. This accomplishment is even more remarkable considering that despite playing only 113 games in 1994, due to the labor stoppage which curtailed that season prematurely, he still was able to attain these lofty numbers, thereby keeping the streak alive. Additionally, there are only 5 other players in history who have both hit more home runs and have a higher career batting average than Thomas (Hank Aaron, Jimmie Foxx, Babe Ruth, Alex Rodriguez and Ted Williams).
In just his first full season, in , Thomas finished third in MVP voting with a .318 batting average, 32 home runs, 109 runs batted in as well as walking 138 times. He won the first of four Silver Slugger awards, and led the league in on-base percentage, something he would accomplish four times throughout his career.
In 1993 and 1994, Thomas won back-to-back Most Valuable Player awards. In 1994, the baseball season was shortened due to a players' strike and perhaps no one felt the sting of the strike more than Thomas, who stood poised to achieve one of baseball's most prestigious honors: the Triple Crown. Not since 1967 had any player finished the regular season first in average, home runs, and runs batted in. Thomas was contending for the honor when the strike occurred, and his numbers were good enough to earn him a second American League Most Valuable Player award. Pressed by the media to comment on his accomplishments—and his future—Thomas told the Atlanta Journal and Constitution: "I'm not into being known as the best by fans or the media. I care how I'm perceived by my peers. I can settle for the label 'one of the best' because that means you're considered an elite player."
He is one of only two first basemen in history to win consecutive Most Valuable Player awards in the major leagues (Hall-of-Famer Jimmie Foxx is the other, in 1932–33). In his second MVP season, he hit an incredible .353, with 38 home runs and 101 RBI. Thomas now proved himself as not only a power hitter, but an excellent overall hitter. He became the most feared hitter in baseball. Pitchers began to pitch around him more often. He continued his trend of hitting for power with high averages. In 1996, he hit .349 and mashed 40 homers and became an all-star for the fourth time. He was 8th in MVP voting.
He rebounded in 2002, but he just hit .252 in 148 games, a career-low for Thomas for a complete season. As the years went on, Thomas' average dropped year after year, but his power never seemed to diminish. Thomas has always been one of the most patient hitters in baseball, leading the American League in walks four times. Through the end of the 2006 season, Thomas was second among all active players in walks and third in on-base percentage, and ranked among the top 20 lifetime in both categories.
Thomas had been maligned by the media in Chicago due to a dropoff in his performance later in his career. Much of this came about after the season, when the White Sox invoked a "diminished skills" clause in his contract. Thomas somewhat resurrected his career in ; although he hit a subpar .267, he was tied for second in the American League in home runs (42), and was in the league's top ten in walks, extra-base hits, slugging percentage, and on-base plus slugging, as he led the major leagues in fly ball percentage (54.9%). In 2005, Thomas hit 12 home runs despite only having 105 at-bats in 35 games, demonstrating the power that he showed earlier in his career. Adding together 2004 and 2005, he had fewer than 350 total at-bats because of the injuries but managed to hit 30 home runs and draw 80 walks. As a member of the White Sox, Thomas and teammate Magglio Ordóñez tied a major league record for back-to-back homers, with six in one season. Thomas won a World Series title with the Chicago White Sox in 2005, but he was not on the post-season roster due to injury. During Game 1 of the Division Series against the Boston Red Sox, Thomas threw out the ceremonial first pitch. "What a feeling," Thomas said. "Standing O all around the place. People really cheering me. I had tears in my eyes. To really know the fans cared that much about me -- it was a great feeling. One of my proudest moments in the game."
“I’ve got a lot of respect for Jerry Reinsdorf, I do. But I really thought, the relationship we had over the last 16 years, he would have picked up the phone to say, `Big guy, we’re moving forward. We’re going somewhere different. We don’t know your situation or what’s going to happen.’ I can live with that, I really can,” Thomas said. “But treating me like some passing-by-player. I’ve got no respect for that.” Thomas said he wasn’t bitter or angry and had joined the A’s with an open mind.
Williams fired back at Thomas calling him an "idiot". He also said “If he was any kind of a man, he would quit talking about things in the paper and return a phone call or come knock on someone’s door. If I had the kind of problems evidently he had with me, I would go knock on his door.”
Despite this controversy, Thomas' statistical legacy from his time in Chicago is significant as he is probably the best player the White Sox have ever had. Thomas has several White Sox records to his name, including all-time leader in runs scored (1,327), home runs (448), doubles (447), RBIs (1,465), extra-base hits (906), walks (1,466), total bases (3,949), slugging percentage (.568), and on-base percentage (.427).
The Athletics installed Thomas as their everyday DH. He started the season slowly, but ended the season as the team leader in home runs, RBI, slugging percentage, and on-base percentage. He provided a powerful right-handed bat in the middle of the lineup for the division-leading Athletics. He had a stretch where he hit a home run in six straight games.
On Monday, May 22, 2006, Thomas homered twice in his first game against his former team. Before Thomas came up to lead off the 2nd inning, a musical montage played on the Jumbotron at U.S. Cellular Field, paying tribute to Thomas's legacy with the White Sox. He was cheered in his introduction by the White Sox fans. Moments later, when he hit his first home run of the night to put his former team behind in the score 1–0, he was loudly cheered along with a standing ovation.
Thomas rejuvenated his career playing with the Athletics, placing fifth in the American League with 39 HRs and eighth with 114 RBIs. He also was key to the team's stretch drive to the playoffs: for the week ending September 10, he was the American League's player of the week after hitting .462 with five homers and 13 RBIs. The 2006 post season provided Thomas the opportunity to play in his first postseason games since 2000 since he missed the 2005 playoffs with an injury, when the Athletics clinched the American League West title, defeating the Seattle Mariners, 12-3 on September 26. During the A's first playoff game on October 3, Thomas hit two solo home runs, leading the A's to a 3-2 win over the Minnesota Twins. His performance during the opening playoff game earned Thomas the distinction of being the oldest player to hit multiple home runs in a Major League Baseball postseason game.
On October 7, 2006, he finished behind Jim Thome, the man who replaced him as the Chicago White Sox's DH, in the voting for the American League Comeback Player of the Year Award. However he was awarded with the AL players choice award for Comeback Player. He finished 4th in the vote for the American League Most Valuable Player Award.
On November 16, 2006 Thomas signed a 2-year, $18.12 million contract with the Toronto Blue Jays which was officially confirmed on November 17, 2006. According to BlueJays.com, Thomas was scheduled to make $1 million (US) in the first season (with a $9.12 million signing bonus) and $8 million in the next season. The contract included an option for 2009 contingent on his reaching 1,050 plate appearances over the next two seasons or 525 plate appearances in his 2nd year of the contract.
On June 28, 2007, Frank Thomas hit the 500th home run of his career, becoming the 21st player in the history of Major League Baseball to do so. It was a three-run shot off Minnesota's Carlos Silva. This is also notable, as Thomas was ejected in the later innings of the game for arguing balls and strikes with the home plate umpire.
On September 17, 2007, Frank Thomas hit three home runs in his team's 6-1 win over the Boston Red Sox. It was the second time in his career that Thomas hit three home runs in a game, the first time also against the Red Sox, on September 15, 1996, in a Chicago White Sox loss. Knuckleballer Tim Wakefield started both games for the Red Sox, and gave up five of the six home runs Thomas hit, including all three in the first game.
During Spring Training in , Thomas expressed his confidence about his team's chances for the upcoming season. Thomas hit his first home run of the season against the Red Sox on April 5, in a 10-2 Blue Jays win. The following day, with the bases loaded and a 2-2 tie, Thomas hit a Grand Slam home run off Red Sox reliever Manny Delcarmen, leading the Jays to a 7-4 victory. On April 19, before a game against the Detroit Tigers manager John Gibbons announced that he would be benching Thomas for an undisclosed period of time. The benching angered the 39-year old Thomas who did not shake hands with his teammates following their victory on that day and said before the game that he was angry and that his career "will not end like this". Thomas signed a two-year, $18 million contract with Toronto in November 2006. The deal included a $10 million option for 2009, but only if Thomas made 376 plate appearances in 2008.
In 1995, a Super NES baseball video game titled Frank Thomas' Big Hurt Baseball was released for home video game play, and Premier Technologies created a "Big Hurt" pinball machine, (marketed under the Gottlieb trade name). Thomas made an appearance in the documentary The History of Pinball in which he discusses the similarities between playing baseball and pinball.
In 2007, he appeared in a promotional advertisement for the Toronto Blue Jays, in which he engages in a pillow fight with children. This ad drew the criticism of the Television Bureau of Canada, who requested a "Dramatization. Do not try this at home." disclaimer be placed on the ad. A similar warning was placed on teammate A.J. Burnett's commercial. The Blue Jays, humorously, then scheduled a "Frank Thomas Kid's Pillow" promotion for September 2, 2007.