I disagree. I don't like the wait for free agency to start.
FREE AGENTS
It is free agency that meets almost all of the needs for the current season. Free agency should start as soon as possible. This way, there will be there first wave of free agents, and negotiation through the time of the combine, and a second wave of free agents singing before the draft.
Most teams don't need to know what rookie might be available to choose their free agents.
Personally, I want the FREE AGENTS on board as soon as possible so that they can learn the playbook and participate in informal meetings and practices (as Amendola did).
ROOKIES
The combine needs to be delayed because of the college playoff series and insufficient time to prepare. Way, way to many players are now skipping the combine. If it stays where it is, even more will skip in the future.
Moving the draft is more minor thing. There is no change in the number of practices. The only thing that changes is the time between OTA's and camp. The rookies won't get to study their playbooks for as long. I don't think that the extra 3 weeks of study means much. The CBA changes in practices and subsequent changes in practices last year were more harmful to rookie development.
BOTTOM LINE
I always err on the side of helping the veterans, our current stars, rather than our stars of the future. I suspect that the NFLPA agrees.