The max rank does not tell you anything. The current rank is only valid after 100+ matches. But the game can think your hidden elo is higher or lower based on your gamestyle (how you get points in a round) compared to the winning rate (and flawless or 5/4 rounds win) and the KD with some fancy math calculation.

Thermite, sledge, flores, recruit, capitao, gridlock should get a shield.