Jordan, widely acknowledged as the greatest player in basketball history, is more supernova than superstar. He left the Chicago Bulls for the better part of two seasons in the mid-1990s to play professional baseball. Then he left the NBA for three more seasons in the twilight of his career, before two final displaced seasons with the Washington Wizards. By restoring those missing seasons, Jordan projects as the only 40,000-point scorer in league history, and he adds more than 2,000 rebounds and 1,000 assists to his career totals. (Projections made by ESPN.com Insider Kevin Pelton.)

The sports world was stunned in November 1991 when one of the NBA's biggest stars announced he was retiring from the Los Angeles Lakers at age 32 after contracting HIV. Fortunately, Johnson is alive and well today. He competed with the 1992 U.S. Olympic men's basketball Dream Team and briefly returned to the Lakers in 1996. Johnson was still near the top of his game when he retired, and his projected statistics reflect that fact. Even accounting for decline, Johnson figured to be an effective player through the 1997-98 season, boosting his number of career games by a whopping 56 percent (from 906 to 1,413). (Projections made by ESPN.com Insider Kevin Pelton.)

Koufax battled control problems over the first six seasons of his career before embarking on an era of dominance in his mid-20s. The lefty turned the corner in 1961, earning the first of six consecutive All-Star berths. In his final five seasons, he won three Cy Young Awards, posting a 111-34 record with a 1.95 ERA and 1,444 strikeouts. Arthritis in his pitching elbow led him to retire at age 30 after the 1966 season. If he had remained healthy and continued to play 11 more years, he would be No. 4 on the career strikeouts list and No. 11 in victories. (Projections made by ESPN.com Insider Dan Szymborski. Rankings through Monday's games.)

Arguably the greatest hitter in baseball history, Williams lost the better part of five seasons of his playing career while serving in the military during World War II and the Korean War. Given that Williams has the MLB's highest career on-base percentage, his statistical projections for those years are especially intriguing. With the starts projected from 677 additional games, Williams would become No. 1 in career RBIs, a healthy 210 ahead of record-holder Hank Aaron. Williams would also climb to No. 6 in home runs and No. 10 in hits. (Projections made by ESPN.com Insider Dan Szymborski. Rankings through Monday's games.)

Borg's most ardent followers mourn what could have been had he not quit for the first time at 26 then slogged through several failed comebacks. They insist he's the best male tennis player ever, not Roger Federer. But Borg's actual Grand Slam total puts him squarely in the middle of the pack with Rafael Nadal, Pete Sampras and Rod Laver. Even his projected total of four to five more, had he played on, still leaves him shy of Federer, who has won 17 majors so far and may have one or two more Slam titles in him. (Projection made by tennis analytics expert Benjamin Tom by hypothetically extending careers to match the trends displayed by other Grand Slam champions who had full careers.)

One of the most skilled and artful players in hockey history, Lemieux missed the better part of three seasons battling back injuries and Hodgkin lymphoma. Then he retired at age 31 in 1997, frustrated as the NHL trended toward clutching and grabbing over skill and playmaking. At Lemieux's peak, he was a more prolific scorer than even Wayne Gretzky, and he returned to the NHL in 2000 and played in parts of five more seasons. By virtually restoring those lost years, Lemieux projects to climb to No. 2 on the NHL's career goals and points list and No. 3 in assists. (Projections made by ESPN.com Insider Rob Vollman.)

While it was a shame to see the reigning MVP retire at age 30 prior to the 1966 season, he likely had only one big year left in the NFL. Running backs generally decline in their 30s, and this was even more true in the 1960s. In that entire decade, John Henry Johnson was the only back to play significant time after age 31. Brown also would have shared carries more and more each year with rising star Leroy Kelly, a fellow Hall of Famer who was just 24 when Brown retired. (Projections made by Aaron Schatz of Football Outsiders.)

Sanders likely would have lasted longer than Jim Brown, as the top running backs were more likely to play into their 30s in the 1990s than the '60s. But not much longer. Marcus Allen was the only contemporary of Sanders who was effective long after turning 33. It's also unlikely a 30-something Sanders would have rebounded from the big drop in yards per carry between his legendary 1997 season (6.1) and his more pedestrian final season in 1998 (4.3). Interestingly, according to the projection, Sanders' career rushing total would have fallen 3 yards short of Emmitt Smith's NFL record. (Projections made by Aaron Schatz of Football Outsiders.)

The hard-hitting Seles was a brilliant, enigmatic presence who won her first Grand Slam singles title at 16 and had eight by her 20th birthday. She eclipsed Steffi Graf for No. 1 in 1991 and '92 and had nearly leveled their terrific head-to-head rivalry at 4-5 when a deranged fan of Graf's stabbed Seles in the back during a match changeover in Hamburg, Germany. Seles missed two years and was never the same. Given her 3-1 record against Graf in Slam finals, Seles' projected total of 15-16 Slams seems reasonable. So does the argument that Graf wouldn't have gotten 22 major titles had Seles not been harmed. (Projection made by tennis analytics expert Benjamin Tom by hypothetically extending careers to match the trends displayed by other Grand Slam champions who had full careers.)

Puckett is one of the most beloved athletes ever in Minnesota, a 10-time All-Star who helped lead the Twins to World Series championships in 1987 and 1991. Although his career was cut short by glaucoma at age 35, he still earned induction to the Hall of Fame on the first ballot in 2001. If we turn back the clock and grant a healthy Puckett six more seasons, he projects to eclipse the 3,000-hit plateau and approach 1,500 RBIs. (Projections made by ESPN.com's Dan Szymborski. Rankings through Monday's games.)