It wasn't the translation at all, in fact the lines are untouched AFAIK. It's the performances. Mei Ling's accent is the most noticeable change, but there's tons of little things. In general it feels a lot less passionate and emotive than the original performance.
In general it feels a lot less pationate and emotive than the original performance
Yeah they do that. My theory is that it's to do with the size of the investment and return, for both games and anime.
e.g. just for the sake of pricing consider an anime, where they spent $500K on visuals for every episode. They have a lot of money already invested in graphics, so they don't want to skimp on something cost-effective like sound. Audio is cheap compared to graphics, so they don't mind spending money there to make the series pop out more, e.g. by hiring popular voice actors. The voice actor has a vested interest in doing a good job, since they have a fanbase and are getting good paid work which enhances their profile. Putting in a substandard performance jeopardizes that.
But then you get the importer/dubber. They're usually a small outfit trying to keep costs down, and most of their costs are actually the dubbing itself. The series is already likely to sell a fair amount based on what the Japanese already put together, regardless of the English voice acting they use. So for those sorts of localizers, there's almost no financial incentive to go "above and beyond" with the dubbing.
And voice actor fandom is different too. In Japan, a new show is announced with a role
planned for a specific voice actor. So they play off whatever known quirks that person has in how the role is delivered. So there's a synthesis e.g. Kugimiya Rie and how she often plays irate lolis. Even if those roles were from another source, their anime incarnation was planned as a vehicle for her, because she's known for a certain type of delivery for that type of character. So the roles are partially built around who's playing them. But in America they hire unknown people to reprise roles that were built for someone else.