Explain Ships Arena to me please..

Been playing since release and I've never understood ships arena quite well. My zzVader has all potency mods, bobs fett has a 2 set potency mod, and my first order tie pilot also has potency and speed mods just for ships arena. However my ships almost hardly ever stick target lock when I feel they should, so that my biggs gains taunt and builds protection. Yes, we all know that ships depends on target lock and biggs survival to win every battle but can someone tell me why my target lock never sticks with high potency and the npc will stick target lock almost every single attack? Is that just a bug, maybe end gane teams have high tenacity and I can't hit my zzvader through that? Asking for a friend of course cause I'm too good to know that my target lock should stick with a zzvader potency build