Fresh baked said not much impact, you might see people come in at night but the event is during the day until like 7 or 8 PM...so most will be busy with that over the parks
It may even be better this year since 12,000 of us will be at events at the Honda center in the evening which is new. 7pm Fri & Sat & 5pm Sun, plus the recommended 1.5-2 hours to get there.
As a local, I can't imagine it taking 1.5-2 hours to travel 2.7 miles from the convention center to the Honda Center. I think they are adding time for things like lines for the shuttles, security, bag check, etc.
While there may or may not be any impact during the event there may be a slight impact the days before or after the event. I know if I was going to the event I would be tagging on a few days for the parks.