Tank usually wins with enough stims (when they know what they are doing), I think the odds are in their favor of not being disabled or DPS'd down (before they can heal) by other builds unless they get lucky or take full advantage of their range/invisibility/high damage rate along with a little luck.
And by tank I mean 6-8 tank perks, along with 6 ST, 10 EN and a reasonable luck to help vs bypasses.
Also with that said, sometimes all it takes is one good crit and it can be game over for anyone, including tanks.