Yes. In athletics for instance it's very easy. Each sport has a built-in scoring system from the get-go. I would also say it's pretty easy to pick out the best scientists. Simply evaluate the improvement in predictive power that their contribution to the field elicits, and I think Einstein, Feynman, et al. would fall out pretty easily as the best.

Many competitive sports are strongly context-dependent, though--just like art. Part of the beauty of basketball, for example, is we will never know if Wilt Chamberlain or Michael Jordan or LeBron James is really the greatest basketball player of all time because they played in different eras. Athletic training was so much different in Chamberlain's era that it's tough to predict if he'd be as dominant today. Even in the early years of Jordan's career, plenty of players didn't lift weights for fear of becoming too bulky.

Sports where competitors are measured against a clock or a tape measure are easier to compare across eras but even then equipment changes make it difficult. Pole vaulting, for example, became a completely different sport when flexible fiberglass poles were introduced. Major track events were still being run on cinder tracks into the 1970's.