I was talking about with day games. They could make it so the last train of the night holds at SEC to allow Meadowlands customers to board. They would have to put up signs saying to let the people going somewhere other than NYC board at Meadowlands first.
One of the issues I've found is that they don't really control boarding at SEC. It's sort of a free for all to try and get on. One time I rode the Meadowlands train and they were delayed almost 10 minutes trying to close the doors. At Meadowlands, they have a queue set up and they open the first car, fill it up, then close it and move onto the second car, close that one up, and so on until all cars are full. Maybe setting up a queue and having more security guards directing traffic at SEC would help speed things up.
As for running the 10 car Multilevel sets like they did for the superbowl, I don't think it's really practical. If you remember, for the Superbowl, they started running single level trains on that RVL about a month out, because they had to break up the normal sets to assemble them for the Super Bowl. That's not practical to do for every event. Better to just run what the biggest sets they have in normal diesel service.
Although the Meadowlands service is by no means perfect, I think it's a great that so many people are riding public transit to get to the stadium, and it has been more than worth it to build the line.