And that's why humans got also skill called "dodge". Makes nice evasions, and sometimes saves your lives. And hindrance sometimes, especially in narrow corridors.´But to the point...
Tyrant IMO is excellent big alien class to divert the fire from other essential base-destroyers of adv. marauder and adv. dragoon. Almost all humans direct their fire on it + the turrets, so rants give them attack of opportunity.
And rant is quite weak in large, open areas, where humans spread out, and rant must to focus on one human, or - mostly, - try kill/wound much as it can. Hallways... ready your dodge, and don't lean to pillars, blocks et cetra. 5 group of normally armored humans in narrow hall are quite temptation. and if rant can barely fit in it... well. We can guess what happens if someone knows how handle trample. after then, tyrants are badass killwhores. So, i think it's justified the low amount of HP and weak escape chance. In narrow maps, of course.
So the question was: Tyrant overpowered?
My personal answer : No, not at all.