I would remove the word "total" in the title....its not just random events. Draft picks are like lottery tickets, I think that is a good analogy. But your chances of hitting on a 100 million dollar hit are way better based on the draft position, especially at the top of the first. You can find a HOFer type anywhere, that is a fact but statistically they come from top 10 picks overwhelmingly more often than after that. Why dont teams just collect picks all the time?
1. You might have a deep roster and you know some of those lottery tickets take time to develop. You dont have a spot on your roster to wait to see if the pick develops
2. Other teams have to want to give you more picks for your pick(s) or for players. It's not just a grocery store you go buy stuff, it takes two. There are a set finite number of draft picks in the market place
3. The work teams put into the draft does have meaning, some are better than others but you must have a grading system and when a guy stands out compared to the rest of the field, it can make sense to trade up. So do teams over-estimate their skill? Probably so, I think it is inherent in the process. They have a lot of money and people and data to throw at the problem, of course they believe in what they are doing.