re: How did Hank Aaron hit so many homeruns being as small as he was?

Hank was considered small for a HR hitter while he was playing. The big guys were Mantle, McCovey, Boog Powell, Frank Howard... Killebrew and Mays were not tall but they were much more muscular than Hank.

The slugger most similar to Aaron in physical appearance was Ernie Banks. Banks started as a shortstop before moving to 1B. Like Aaron he did not hit towering HRs. Just enough to get over the fence.

Even smaller was Jimmy Wynn of Houston. He played in the Dome when it was nearly impossible to hit long HRs. He was called 'The Toy Cannon.'