The Dallas Cowboys' use of $50.1 million cornerback Brandon Carr as a nickel safety against the Tampa Bay Buccaneers last week was born out of necessity.With free safety Gerald Sensabaugh sidelined with a calf strain, the Cowboys felt Carr had the best combination of size and athleticism among the cornerbacks to make the move and help the team. That Carr was willing to move showed his team-oriented attitude, which is another reason why the Cowboys were excited to add him as a free agent from Kansas City in the off-season."Brandon embraced this," coach Jason Garrett said. "He saw how he could help our football team absorb an injury."Sensabaugh should be back for the Chicago Bears game on Monday. But with strong safety Barry Church out for the season with a torn Achilles' tendon, Carr might be called on again to help out at safety. The Cowboys have yet to make a final decision.Either way, Carr joins an elite list of Cowboys whose greatness was founded or enhanced by their in-game and in-career position flex and versatility.S/CB/KR Mel RenfroThe epitome of versatility. Renfro was a two-time All-America running back in college at Oregon who moved to defense after being drafted by the Cowboys in 1964. He made the Pro Bowl at safety in each of his first six seasons then moved to cornerback and made four consecutive Pro Bowls, making him arguably the best safety/cornerback in NFL history. He led the NFL as rookie in kick and punt returns and had seven interceptions. He is still the team leader with 52 career interceptions, including 30 during his first six years at cornerback. His 26.4-yard career kickoff return average is also a club record. In the 1971 Pro Bowl, Renfro started at cornerback and returned two punts for touchdowns, earning Most Valuable Player honors in the NFC's 27-6 victory.S/CB Darren WoodsonAn undersized linebacker in college, Woodson moved to safety after being drafted by the Cowboys. He proved to be a hard-hitting strong safety who had the range of a free safety and the coverage ability of a cornerback. He is the team's all-time leading tackler and a five-time Pro Bowler, arguably the Cowboys best safety and best special teams player. It was the Cowboys' use of him as a nickel cornerback covering slot receivers on passing downs that really stands out. Playing close to the line allowed him to support the run, pressure the quarterback as well as cover receivers such as Hall of Famer Jerry Rice in the slot. It made him the most versatile safety in the league but hurt his overall numbers, as he was unable to pile up interceptions.OG/OT Larry AllenThere has never been any questioning Larry Allen's greatness and dominance as an offensive lineman. He is a member of the NFL All-Decade team of the 1990s and 2000s. He made 11 trips to the Pro Bowl in 14 seasons in the NFL. A career guard, Allen started at left tackle in 1998 and made the Pro Bowl. He is one of three players in NFL history to make the Pro Bowl at two line positions. Allen played right guard, right tackle, left guard and left tackle during his career. It was in 1997 when Allen helped invent a new position for the Cowboys, the nickel tackle. George Hegamin replaced injured Mark Tuinei at left tackle midway through the season. He was a good run blocker, but weak pass blocker. For a two-game stretch, the Cowboys moved Allen from guard to left tackle on passing downs to protect Troy Aikman's blindside. He did it so well, he became the full-time starter there for the final four games of the season.CB/WR/KR Deion SandersDeion Sanders is the ultimate Mr. Versatile. A former football, baseball and track standout at Florida State, he joined Bo Jackson as the most decorated modern-day, two-sport professional when he played in the NFL and Major League Baseball at the same time. In 1998, he became the first player to hit a home run and score a touchdown in the same week. He is also the only player to play in a Super Bowl and in the World Series. His versatility in football was always evident during his Hall of Fame career because of his shutdown play at cornerback and game-changing play as a returner. He joined the Cowboys in 1995 for a then-record $13 million signing bonus for the chance to win back-to-back Super Bowls and the opportunity to play receiver on offense. In helping the Cowboys beat the Pittsburgh Steelers 27-17 in Super Bowl XXX, Sanders started at cornerback, returned a punt and caught a 47-yard pass to set up the first touchdown. He went on to make eight starts at receiver in 1996 because of injuries, as well as play at cornerback, catching 36 passes for 475 yards, ranking second on the team in receiving yards.