Once you get past the first 2 picks...the draft is so difficult to predict that teams have to have a list of (for example) 7 guys they'd consider choosing between, and then other options should someone like Aaron Rodgers drop or should all 7 of your guys be picked. Those "bring in and never take" people can be done for a number of reasons...actually wanting to draft a guy, smokescreen, but the one thing you can definitely say is that you're getting more information on a guy. That information may not always be positive. You may bring a guy in wanting him to step up and show you something new and he doesn't do it.