I've seen a similiar version of this before but anyway is still painful that Grievous by Genndy Tartakovsky is non-canon. Seriously he's one of the best designed characters in the series and got one hell of a nerf.
They turned him into another Boba Fett:looks badass and cool but is a wimp.

(At least is not as bad as Captain Phasma)

Legends General Grievous, a terrifying mix of a Xenomorph, a Predator and a Terminator that didn't even need his extra arms to take on 5 jedi masters at once and win.
Canon General Grievous, a mustache twirling villain that get defeated by a lone jedi padawan, out smarted by Jar Jar Binks, constantly needs back up and only ever wins when he has an unfair advantage.
Side note: I actually like his canon origin more as it makes him less sympathetic and a Darth Vader copy and more of badass that dared to fight against the force through skill and technology. Too bad he wasn't able to back that boast.