Nr of cars vs congestion follows an S-curve with a very narrow/steep middle section. Removing a single digit percentage of cars/passengers can mean the difference between 'busy but only a little slow down' and 'complete stand still'. I don't know about the numbers in this specific case, but transport systems work in not very intuitive ways.

It removes those 5% from clogging up the roadways and parking lot. If you attend games, why would that be a bad thing?

Faster, cheaper (than car) and with less emission right? Seems quite good to me.

Don't underestimate that if those 5% instead of taking the car take this Loop, there'll be less cars and less traffic. So a higher % will be home faster.