Gary Glick of Synergy Sports, Inc. (not to be confused with Synergy Sports International) has a nice Q&A segment called Sports Agent Corner at the website Midwest Sports Fans.
It’s a short read, so I suggest you check it out by clicking the link to the Sports Agent Corner above. Most insightful is the last question and answer:
MSF: For all of the fans who do not understand it, describe a little more about what happens after the last pick of the second day. What is the ensuing scramble to get your undrafted players into camps like?.
Gary Glick: Most of the Undrafted Rookie Free Agents (those players not drafted) are signed within 2-3 hours after the draft. It is imperative that we start calling at the end of the 7th round and make as many calls and as quickly as possible to all of the NFL contacts we have. I usually have 2 phones going at the same time! I have never seen so many calls being made so quickly.