Here's a biggie that's true of HBD that is new (compared to Sim).
Players do NOT have a set position. Their skills dictate the position, not the other way around. In other words, you might have a "shortstop" with lousy range, but a great arm. You can make him a 3B or RF with no positional penalty.
Don't assume that the player is slotted correctly when you get your team.