Posted 13 March 2012 - 03:23 PM
That's a good question and I don't know if there's a good answer for it. There are many answers probably. here are some and people can add to this:
1.) Scouts/Draft people love athletes. That's why you see a ton of SS and a ton of CF drafted. Why? Because athletes can move. They're obviously not all going to play SS or CF, but SS can generally move around the infield and some outfielder, and CF should be able to play the corners.
2.) Growth - high school draft picks are 17-18 and from the time they get drafted through the 4-6 years that it takes to move up, they can grow several inches and/or several pounds. For instance, Miguel Sano signed as a SS but he's now huge and likely profiles better at 3B, so they moved him.
3.) major league need - Look at the Royals. They signed Salvador Perez to a long-term deal and he's only caught like 35 games for them. One of the Royals top prospects is Wil Myers who caught the first few years of his minor league career, but last year, he was moved to RF. The Twins are good about making sure players can play multiple positions in the minor leagues because you don't know where the big league clubs' needs will be in 2 years much less in 5-6 years when the player is drafted.
Anyone else have other reasons? Obviously some get drafted as position players and that doesn't work out so they move them to the mound.