Everyone I asked told me Marcelo was trash, and to get any other lb, just not Marcelo. I got him anyways, and wow I don't regret it. He can dribble his way past any defenders, his 5 star skills might have something to do with that, and he has more pace than it seems, and can keep up with nearly every winger i come across. His defending is out of this world too, making every tackle i want him too, and intercepting the ball without me even trying to. He can pass from anywhere, dribble past anything, and even has a decent shot on him. The only thing I would say was wrong with him was his size, meaning he'd lose most headers. This doesn't mean much though, since he'd dispossess them seconds later. This is purely my perrsonal opinion but, Marcelo is better than Mendy, Telles and every other lb i've used.
He excels in anything you want him to, an absolute beast of a player.
As an attacking lwb, he will absolutely ruin any opposing wing-back, and as a defensive lcb, he will stop even the best of players.
Height means jumping is not great, but he doesn't get pushed off the ball easily.