I think old ratings (pre dugtrio) are outdated for certain pokemon (blaziken, dugtrio, rhydon...pretty much anything dugtrio could trap),
It's speed is way too low to give it a purpose against anything that isn't a wall, unless you run a choice band maybe.
It's no sweeper and requires good predictions to work as intended.
Possibly an a+, but i don't feel it should be that close to an S rank when it's worn out so easily.
Both ratings can work i suppose.