What is the Joe DiMaggio effect?

Joe DiMaggio becoming the first baseball player to earn a contract worth $100,000 dollars. While the question "What took so long?" may pop into your head (he received that contract in 1949 as a 34-year-old, after all), the decision to give him that contract may not have been so obvious.

Joe DiMaggio was the best baseball player of his era. He was the first baseball player to earn a contract of $100,000.