Using Umtiti,Roberto and Mathieu as LB backups for Alba feels like a band aid on a huge wound that needed attention ages ago.
We really can't keep doing this. Mathieu originally was a LB, but those days are long gone as he clearly struggles playing in the role now and with his ankle and calf problems he's better off playing CB for now on.
Roberto while he's capable of playing RB, with him being right footed he's clearly limited playing as a LB compared to RB.
Umtiti just got here and again he hasn't played LB much in the last three years like Khaled said. He's a CB and it should stay that way.