you chose pictures of first basemen who are usually big because theyre usually home run hitters. and you chose specifically fat pitchers, you ever heard of CC Sabathia? yea he's huge, and hes one of the best at throwing a baseball in a way such that nobody can hit it. there are 7 other positions on the field that require running constantly (minus catchers, but their position is one that requires a ton of brains and quick movements to hop up and throw out a baserunner).
if you are a football fan then you should understand the importance of varying body types per position.
heres Ryan Braun, he stole 30 bases and hit 30 home runs the past 2 years. (you should be impressed given your point that stolen bases are rare)
^^ no flubber on that dude.
serriously just go through a batting order and read the players stats. most guys will be in incredible shape. obviously since theyre the best in the world and get paid millions to be the best at it, but just do it anyways if you still done believe me
Jose Reyes should really lay off the Cheesie Poofs eh??