How much of a prospect is a guy who 21 and fully physically mature compared to an 18 year old? Teams will project where the 18 year old will be in 3 years of development and compare that to where Howard is now.
I could see a club trading a 21 year old AHL player for Howard though. An apples for apples trade.
It's literally a matter of projection. Not many prospects you're going to project to win the Baker.