IS having TestAmenT as an opening band a bad choice for Anthrax?

So, which is it? Is Testament diverse or pure? You can't be both.

They are 100 percent a thrash band. But they are not one dimensional like some tend to think. They prove you can remain thrash while still having diversity from album to album. To evolve or grow as musicians you can do it without changing your sound to some mainstream rock garbage like some of the so-called thrash bands have done over the years.