Unlike Yasuo Tryndamere can actually reliably reach the backline AND not blow up immediately once he gets there. He can also reliably get out after he's done having his way with you, because he can dash whenever and wherever he wants. And in case that's not enough survivability for you, you also have a heal and invincibility. Oh, and he can also be hard cc'd and still get his ult off. Let's not forget that. And his crits actually do full damage.