Jalen Ramsey actually began wearing the balaclava mask while he was still with the Jaguars and has just continued doing so with the Rams. I've not seen anything which explains WHY he wears it so I can only guess that perhaps it's one of the following reasons: 1) he feels it's fashionable 2) it's to keep his head warm 3) the facial concealment adds to his bad boy persona on the field. In fact, when he was still with the Jaguars, his ski mask was referred to as his "villain" mask 4) it keeps his braids in order 5) he just likes wearing stuff that makes him stand-out and different from everybody else