Which team up counts?

In PvP, if I am attacked I know that it is the last team I won with that is defending but, which team up character would it use if needed. The Left, middle or right one? The last one used? Is it random?

Completely random, TU used, equipped, or in your inventory have no effect on defensive TU selected

Thats interesting since Ive suddenly hit a barrage of 4thor, xforce, Lcap, IMHB, kp, fury, deadpool, on and on that i didnt seem to see more than rarely (if even ever) before the last few weeks. Just got hit with a level 166 LC yellow, caught me by surprise as I never really payed attention to teamups before as the always seemed inconsequential (a few hundred points). Some change i dont know about?