I think it's pretty much always been bad.
But there's a unique issue now where they get good voice actors, but have them perform poorly as though they're directed to do so. It's like they have a set idea of what an "anime dub" should sound like and are trying to emulate that rather than a good performance to begin with.
Makes me think of Batman the Animated Series where they were able to get some really great voice actors, many who had performed in theater previously, due to the dialogue not being tons of yelling or rough crap that would mess up voice actors voices in some cheesier cartoons done prior to it. Instead it was often fairly normal performances. It was like there was a transition to realizing you could treat performances in these cartoons with a bit more dignity and professionalism, which I think has been absent from anime dubbing.
With anime dubs it often seems like they have a hard time treating it as something serious, instead wanting to do this intentional cheesiness or emulating the crappy dubbing of the past. May also be connected to many voice actors thinking of anime as solely for kids and imagining it needs an intentional goofiness to it, due to looking down on the idea of a kid's property being treated with any seriousness (in terms of professionalism).