So, what’s a T-Line? It’s considered to be an advantageous position that you establish on your opponent (an opposite handed-fighter). In reality, T-line is nothing but taking foot dominance to an extreme level. And if you’re on the receiving end of T-Line, it’s perhaps the most dangerous place to be in a boxing ring.
Check out this illustration below, herein the Southpaw is on the outside of the conventional opponent’s left shoulder. This allows Southpaw to attack with both hands whereas the conventional opponent is mostly limited to no punch. Why? Because if he wants to use his left hand, he’ll have to do so in an awkward angle with minimum effect and if he’s do use his right hand, he’ll have to swing it all the way over Southpaw’s left shoulder leaving his own body and face vulnerable.