Definite upgrade for me. I don't know why I have this opinion but I actually think McCarthy would be a decent defensive full-back.
I remember he played there against WBA last season at the Hawthorns when Coleman went off. As an alternative in desperate need yeh it worked, but he's a midfielder IMO.
Honestly, he gets so much stick and while fair enough for some of it, on form he's easily one of our better players. He needs to re-find it though and prove he can be good enough to stay. I think next to somebody like Carvalho, he could thrive. I actually think that would be a better pairing for certain games than Carvalho and Witsel, tbh, though wouldn't complain if we got the Belgian lad as well...