He was the best center fielder in the history of the game and many say he was the best all around player.

ESPN says Mays brought joy to baseball,
"The 20-year-old kid with the bright, boyish smile entered the majors tentatively, like a child peeking into a forbidden room. But he soon realized that he did indeed belong, that he wasn't an interloper. Not only did he play the game with extreme skill, but for most of his 22-year career, he made the game seem like, well, fun."

There are many pictures of the famous catch he made in the 1954 world series, but most experts say that Mays' quick relay throw from deep center field was the most important part of the 1954 play, the catch itself being merely a matter of Mays outrunning the ball. The throw saved a run.
See the catch and throw at YouTube

Links:
- Wikipedia
- Willie Mays' Greatest Play Was Against the Brooklyn Dodgers in 1951 | Bleacher Report
- Willie Mays - The Catch
- The catch and throw at YouTube