When teams make selections in the NFL Draft, there is always some combination of trying to fill needs against picking the best talent available in picks. You rarely see a team pick a player purely because he plays a position of need or purely because he is the best talent available. You have to find value in a pick, but he also needs to fit what you are trying to do. If a player fits both pieces of criteria, it's a dream come true.
As we get deeper into the Draft, the talent level takes a hit. The strategy morphs into purely one of best player available on the third day. Early in the Draft, you can probably find a good player at any position. Now most of the good players are gone. You cannot look to fill needs because there might not be a good NFL player left at the position you are looking for. Even if you do, that player is probably not going to be able to immediately help your team. There is a good chance he has fallen this far because his game still needs a year or two of development.
Early in the day, there still might be enough talent to factor in needs a bit, but that will go away as the day progresses. If you have not filled your needs by now, you probably have missed your chance.