Here's what MLB's biggest stars looked like at the start of their careers

So far this season, every one of MLB's top 10 position players in Wins Above Replacement (an all-purpose stat designed to approximate a player's value) is under the age of 30. With pitchers, the number drops to four out of 10, but all told, it's still a remarkable share for baseball's youth movement.

And yet, some of our favorite players are the ones that manage to hang around for years, delighting baseball fans each and every summer. Impact veterans are only going to get less common as time goes on, so it can be fun to look back at what some of today's established stars looked like when they came up.

Check out how some of the top players in MLB look today versus how they looked when they first got the call.