A perfect game is defined by Major League Baseball as:
An official perfect game occurs when a pitcher (or pitchers) retires each batter on the opposing team during the entire course of a game, which consists of at least nine innings. In a perfect game, no batter reaches any base during the course of the game.
There were 20 of these pitching performances before today, with Philip Humber joining that club as the 21st pitcher to perform such a feat. He helped lead the Chicago White Sox to a 4-0 victory over the Seattle Mariners.
He only needed 96 pitches to get the job done and struck out nine along the way. This may be one of the more unlikely pitchers to do this since he has never thrown a complete game in his 29 career starts.
Now that he has accomplished this feat, the question that is asked is what's next?
Here is a breakdown of how the other 20 perfect game pitchers have performed in their next starts and over the course of their careers.
Lee Richmond threw the first perfect game in MLB history on June 12, 1880 for the Worcester Ruby Legs. They beat the Cleveland Blues 1-0.
Richmond went on to pitch in a league-leading 74 games and finished the year with a 32-32 record. He threw 57 complete games and had a 2.15 ERA that year.
It didn't take long for MLB to get their second perfect game as John Montgomery Ward completed it five days after Richmond. On June 17, 1880, Ward blanked the Buffalo Bison and helped the Providence Grays win 5-0.
Monte is the youngest pitcher to throw a perfect game in MLB history at 20 years of age. He won 47 games in 1879 and 39 in 1880 but struggled after that. He only won 56 games the rest of his career as a pitcher and eventually made the switch to the middle infield.
It took almost 25 years for the next perfect game to be thrown and the next guy to do it has a trophy named after him.
On May 5th, 1904, Cy Young threw a perfect game for the Boston Americans in 3-0 victory over Philadelphia.
Young pitched for 22 years, compiling a 511-316 career record, but went 132-116 over the final eight years of his career. He was inducted into the Hall of Fame in 1937.
Addie Joss threw the next perfect game towards the end of 1908 season on October 2nd. He pitched for the Cleveland Naps as they beat the Chicago White Sox that day 1-0.
His playing career was cut short as he unfortunately passed away at the age of 31, but he still accomplished a lot in nine years. In addition to this perfect game, he threw a no-hitter and averaged almost 18 wins a season with a career ERA of 1.89.
Charlie Robertson was an average to below-average pitcher for most of his career with a record of 49-80. One of those victories, though, was the fifth perfect game in MLB history.
Charlie Robertson threw the first of three perfect games in Chicago White Sox history on April 30th, 1922 against the Detroit Tigers.
What is impressive is that Robertson threw the perfect game in only his fifth career start. However, his next start did not go so well as he gave up four runs in six innings of work in a loss to Cleveland.
He struggled the rest of his career as well, never winning more games than he lost in a season; he finished with a career ERA of 4.44.
Don Larsen threw the next perfect game, the first in over 34 years, as the New York Yankees beat the Brooklyn Dodgers 2-0. Like Robertson, he was an average pitcher but will live in history with this one game.
Larsen is the only pitcher in MLB history to throw a perfect game in the postseason, and actually accomplished it in the 1956 World Series. He won the World Series MVP for his performance.
He pitched well in 1957 in going 10-4, but saw his numbers start to decline and finished his career with an 81-91 record and a 3.78 ERA.
Jim Bunning was the next to throw a perfect game, which happened on June 21st, 1962 against the New York Mets. This was the third perfect game in National League history and the first one since 1880.
His next start came on June 26th and he went seven innings, giving up 11 hits and four runs. He did strike out five and didn't give up a walk. The Phillies ended up getting the 6-5 win over the Cardinals.
He pitched pretty well for the rest of his career after that day, and was inducted into the Hall of Fame in 1996.
Sandy Koufax threw the next perfect game, one year after Bunning, in an L.A. Dodgers 1-0 win over the Chicago Cubs. He accomplished this in the second-to-last season of his career.
He threw the perfect game against the Cubs on September 9th and faced them again in his next start five days later. This start didn't go as well as Koufax was tagged for the 2-1 loss in that game. He went six innings, giving up one earned run and striking out three.
Over his 12-year career he went 165-97, threw three other no-hitters and won the Cy Young award three times in his final four seasons. He also won several other awards throughout his career. He was elected to the Hall of Fame in 1972.
Jim "Catfish" Hunter threw the ninth perfect game in MLB history with the Oakland A's during the 1968 season. However, like most of the pitchers before him, he struggled in his next outing.
He gave up eight hits, eight earned runs and five walks in six innings of work against the Minnesota Twins. He pitched for the A's through the 1974 season before finishing his career with the New York Yankees in 1979.
He ended his career with a 3.26 ERA and a record of 224-166, and was inducted into the Hall of Fame in 1987.
Len Barker threw the next perfect game on May 15th, 1981 for the Cleveland Indians as they beat Toronto 3-0. Even though Barker had a mediocre career he followed up his perfect game with a complete game.
He pitched again on May 20th and went nine innings, giving up three earned runs and only one walk while striking out 10. Barker pitched for the Indians until 1983 when he was traded to the Braves; he retired after the 1987 season.
Barker finished his career with a 74-76 record and a 4.34 ERA. He also had one All-Star appearance in 1981.
Mike Witt threw the 11th perfect game in MLB history and the third in a row in the American League on September 30th, 1984. He threw the perfect game in his last start of the season.
The perfect game did not carry over to the 1985 season as he went 7.2 innings and gave up four earned runs and 10 hits in his first start. Witt had a decent career and even finished in the top three in Cy Young voting in 1986. He finished his career in 1993 with the New York Yankees.
Tom Browning was next to accomplish the perfect game on September 16th, 1988 against the Los Angeles Dodgers. His next start was not perfect-game worthy but was still pretty good.
He was able to pick up the win against the San Francisco Giants, going eight innings, only giving up one run and striking out four. He finished that season with a 18-5 record, but that was the best season of his career.
He pitched seven more seasons after 1988, going 60-50 over that span.
Dennis Martinez pitched in the majors for 23 years and was the 13th pitcher to complete a perfect game. He threw it on July 28th, 1991 for the Montreal Expos in a road game against the L.A. Dodgers.
His next game came against the Phillies on August 2nd and he went seven innings and struck out four. However, he gave up six hits and four runs and the Expos ended up losing the game 6-5.
Martinez pitched another seven seasons and had some good years, such as in 1992 when he went 16-11 with a 2.47 ERA. He also had some bad years, such as in 1997 when he went 1-5 with a 7.71 ERA.
The Gambler was the next pitcher to get a perfect game and did it exactly three years after Martinez on July 28th, 1994, in a 4-0 win over the California Angels. However, unlike Martinez, Rogers had an awful outing in his next start.
On August 2nd, he faced the Chicago White Sox and only lasted 5.1 innings, giving up five runs and three walks in a 6-2 loss.
Rogers went on to have a solid 20-year career, finishing with 219 wins and a 4.27 ERA.
David Wells famously said that he was "half-drunk" when he threw his perfect game against the Minnesota Twins on May 17th, 1998.
Boomer came out in his next start against the Boston Red Sox and had a decent showing, going seven innings and striking out five. He did give up five hits and three runs but still got the W.
That year was probably the best of David Wells' career as he went 18-4 with a 3.49 ERA and eight complete games.
Even though Wells was not always a model citizen, he was still a pretty good pitcher with 239 wins over his 21-year career.
It didn't take long for the Yankees to get their third perfect game, this time by pitcher David Cone in 1999. He shut down the Expos on July 18th of that year as the Yankees won 6-0.
Cone was not carried off the field in his next start, though. He lasted only four innings, giving up six runs, six hits and four walks against the Cleveland Indians.
Cone struggled after the 1999 season, going 14-24 with an ERA over 5.00.
Randy Johnson threw a perfect game against the Atlanta Braves on May 18, 2004 as a member of the Arizona Diamondbacks. This was just another highlight in his Hall of Fame career.
The Big Unit had another strong outing in his next start, going seven innings, giving up only four hits and striking out five against the Florida Marlins.
That year he had a record of only 16-14 but had an ERA of 2.60. This was his last year with the Diamondbacks before he took his talents to the Yankees, then came back to the Diamondbacks before finishing his career with the San Francisco Giants.
Johnson finished with a 303-166 record, was second all-time and first among left-handers with 4,875 strikeouts, threw one other no-hitter and won five Cy Young awards in his career.
Mark Buehrle threw the 18th perfect game on July 23rd, 2009 against the Tampa Bay Rays. Like the majority of pitchers who have thrown perfect games, he struggled in his next start.
He faced the Twins and lasted 6.1 innings as he gave up five hits, five earned runs and only struck out three. He did bounce back and had a solid season, going 13-10 with a 3.84 ERA.
Buehrle is currently pitching for the Miami Marlins and while he has never been an ace, he is an important pitcher in the rotation. He has always been a workhorse and eats up innings. The perfect game was the second no-hitter in his career.
If Dallas Braden didn't throw a perfect game in 2010 he might only be remembered for picking a fight with Alex Rodriguez. He has been a mediocre pitcher for the majority of his career except that afternoon on May 9th, 2010, when he led the Oakland A's to a perfect 4-0 win against the Tampa Bay Rays.
His next start came against the L.A. Angels and he ended up getting the loss, giving up four earned runs and seven hits over eight innings of work.
He currently has a 26-36 career record and 4.16 ERA.
Roy Halladay didn't waste any time getting Philadelphia fans on his side by throwing the 20th perfect game in MLB history on May 29th, 2010, only two months into his first season with the Phillies.
This also came less than a month after Braden's perfect game, which was the first time two perfect games occurred in the same season since 1880.
He had another strong start in his next game, going seven innings, giving up only two runs and striking out 10.
Later that year, Halladay became only the second pitcher in baseball history—Don Larsen being the other—to throw a no-hitter in the postseason when he no-hit the Cincinnati Reds in Game 1 of the 2010 NLDS. It was Halladay's first-ever postseason start. That year he went on to win the Cy Young award.
He has pitched 15 years in the majors and doesn't look to be slowing down anytime soon; he currently has a record of 3-0 and a 1.17 ERA for the Phillies.