whoa now I thought the complaint here was that there was no way for fans to get to the game without a car, if there are so many options, what is the problem?
The problem is that all of the train lines that service the arena go exclusively north/south. Thus for anyone actually living in SJ and not walking distance to a train station, you would have to drive anyways to get to the train station, and for me personally when I lived in SJ (well Campbell actually) there literally was not a train station between me and the arena.
So basically those trains are only viable for someone coming from the SF peninsula or the east bay, or the population that lives near the southern portion of those train lines.
Therefore the only other mass transit option available is buses, which are useless if traffic is the concern getting to the arena, as SJ has no designated bus lanes to bypass traffic, at least when I lived there up until about 4 years ago.
This does not even consider people coming from the greater bay area like Livermore, Pleasanton etc where its a simple 30ish minute drive(without traffic), but hours on public transport.
In short, while there are public transport options at the arena, they all service essentially the same portion of the bay area population north of SJ, and not much of the actual geographic area of SJ(and bordering cities/towns) itself.
edit- I did forget about light rail, which does branch out a bit east and west, thus could be an option for some as well.