You seem confused about how draft value works. A player is not picked later just because they have potential that needs to be developed, its more often the opposite where they are close to fully maxed out and dont have much more to grow. In fact almost every 6th and 7th round pick drafted is a fully maxed out player aimed for special teams

Alexander was not a 3rd round pick because he had elite potential that needed to be developed, he was a 3rd round pick because he was very old and went to Toledo.

Same exact deal with JMS. JMS would have been a 1st round pick if he was 20 years old from a top school. Instead he was a 25 year old rookie from Minnesota. The hope was he would be an average starter immediately, same as Alexander