You are exactly right about Mays .. my point was that even HOF players often struggle early. And Willie was kept even defensively by Leo as the best CF ever..
From SABR
https://sabr.org/bioproj/person/willie-mays/
Manager Tommy Heath informed Mays that he had been called up to the Giants. Mays’ response: “Tell Leo I’m not coming.”24Heath called, and Durocher laid into Mays on the phone. Mays told him that he didn’t feel that he could hit big-league pitching. Durocher, speechless for perhaps the first time in his life, finally broke his silence and asked Mays what he was hitting. Mays answered, “.477.” (He had a current 16-game hitting streak and a .799 slugging percentage, and was on a pace to score more than 150 runs and drive in 120.) Durocher asked, very quietly but with some scatological punctuation, “Do you think you can hit .250 for me?” Mays responded in the affirmative.25 He was on the next plane to meet the team in Philadelphia. Stoneham bought an ad in the Minneapolis Tribune to assuage the local fans’ outrage at losing their young star.
The Giants were 17-19, in fifth place, on May 25, the day Mays joined the team at Shibe Park. Durocher immediately installed the 20-year-old in center field. The Giants won all three of the games in Philadelphia, though Mays was hitless in his first 12 at-bats. Despite his batting woes, when the team returned to the Polo Grounds, Mays’ first home game saw him batting third against the Boston Braves and their star southpaw Warren Spahn. In his first at-bat, he hit Spahn’s offering atop the left-field roof for a home run, his first major-league hit.
After the homer, Mays went on a 0-for-13 slide, leaving him hitting .038 (1-for-26). At this point, in an often-told story, Mays sat in front of his locker, crying, after taking the collar again. Coaches Freddie Fitzsimmons and Herman Franks sent for Durocher. Mays again said he couldn’t hit big-league pitching. Durocher replied, “As long as I’m the manager of the Giants, you are my center fielder. … You are the best center fielder I’ve ever looked at.”26 Then he told Mays to hitch up his pants more to give himself a more favorable strike zone; he proceeded to go on a 14-for-33 tear.