Marcus is far from a “tank”. Sure, if all of his cards are maxed out at 5, he can take a few hits. But a boomshot to the face? Don’t be ridiculous.
Even with his ultimate engaged, a burst of Claw or Hammerburst ammo will down him immediately, even in cover. A boomshot, Dropshot, Salvo, Tri-shot or Mulcher hit will also down him.
Sure, he can take a hit, but he can’t kill anything. Give Del a Claw, and he is just as powerful as Marcus with his Lancer, Hammerburst or Claw. Yes, Marcus can kill enemies with a Tri-shot, but so can every other character.
Marcus is and has been my favorite character. In pains me to say that he is the weakest and least effective character to play as in Gears 5.