Do not purchase parking at the stadium lots... it is way to expensive. There are private businesses that have pay parking on game days all around the stadium. I actually suggest you get a parking lot that is as far away from the stadium as you can....well, within reason. Get something about .5 miles away. When the game ends, traffic will not be moving at all, so if you can walk 1/2 mile away to get to your car, you have a better shot at then kind of driving away.
We always get a hotel room within 2 miles of the stadium on game days. We uber to the game from hotel and then we walk back to our room, which will be faster than trying to drive in traffic that isnt moving. If you have not booked a room yet, I strongly encourage you to do that. It saves you from paying for parking as well as not being frustrated with taking over an hour to get away from the stadium. We come out from Ca and I have gotten the routine down pretty well by now. Ask away and I will answer as much as I can.