Major Conn Smythe thought the name Toronto St Patricks limited their appeal to a small section of the Toronto population. He rechirstened the teams the Maple Leafs because he felt that the Maple Leaf was the national symbol (It wasn't yet on the Canadian flag and the idea for the flag came right off the Leaf's jersey!) He had worn Maple Leafs on his uniform during WWI
Because "Leafs" is a team name and not a leaf on a tree.
Grammatically speaking, this is what's known as a "proper noun".
At our final assembly, please pick up your grammarian award. Short and sweet and most proper.
__________________ Noah Cross: 'Course I'm respectable. I'm old. Politicians, ugly buildings, and ****** all get respectable if they last long enough. Timothy Fenwick Jr: Do you ever get the feeling that there's something going on that we don't know about? Boogie: If you don't have good dreams, Bagel, you got nightmares.