Among all of the drafts for professional sports, there isn’t one that is as much a wildcard than the MLB Draft.
In the NFL, players go straight to their respective teams and play immediately. The NBA, some play right away, others gradually get worked in. Hockey is similar depending on where you get drafted, as it could be years before you make an impact for the team that took you.
When it comes to the MLB draft, a lot of times you are lucky if you get one impact player from a certain class. Players come and go, get stuck in the minors or become barely replacement level players.