"Reach" is an entirely subjective term that means: higher than some sportswriter or fan thinks it should be.

In general, teams don't reach. What each team does is to place a value on a player according to their own estimation and act accordingly. The only way a reach could happen (and it probably never does) is if a team drafts a player long before their own value system says they should, which for me is an oxymoron.

We never heard of a such a thing as a reach until Mel Kiper came along.