Since the draft has recently occurred, Andrew Brandt over at SI.com wrote an article that examines some of the implications of rookie contracts now coming in en masse. The new CBA has expedited the process of signings since it has removed the incentives of the previous CBA for agents to wait until July to sign.
Part of the reason why players and agents would wait is to avoid players in a similar slot in the draft "jumping their slot." Such a thing would hurt an agent's ability to recruit draftees in the future. But, now, with the signings much more regularized, the players don't need to pay an agent his maximum signing fee (3%), and Ereck Flowers is even negotiating his contract with the Giants by himself. The only reason agents even contribute to rookie contracts any more is to assist in debates over the structure of the contract (Brandt does an excellent job laying out some structural considerations).
The result of this change, however, is that agents have a significantly less powerful relationship with rookies than ever before, and they make significantly less money off of first round rookies than under the previous CBA. As a consequence, the agents have been signing their players up for marketing deals (trading cards, locals markets, etc.) at a rapid rate. Agents have lost a large source of income that was available just a few years ago.
But, there are also consequences for the players. First off, they have to work more marketing deals as a rookie, potentially distracting them from OTAs or settling into their new life. The difficulty, moreover, is compounded by the fact that - historically - it can be very hard for certain rookies to transition to the NFL.
And that doesn't even begin to address the issue that veteran members of the players union screwed over their new members to the very same union. There are certainly reasons for this (I mean, the players have never played a snap - but on the flip side, that's not how value is determined for draftees or, really, in any other job ever), but it is still a huge change for rookie players and their agents.