So let’s see what we have here:
FL@k received better shield tech and a loader bot… Sounds like he learned from DLC1 and adopted a loader bot.
Amara now has cryo element… Perhaps from studying and atuning herself to her surroundings on Xylurgos… DLC2
Zane is getting increased Crit, handling and accuracy in his tree… almost like he learned some gunslinging from an old western style environment… DLC3
Moze has lots of explosive power and focuses on one element … Fire… So increasing her fire damage by learning from another vault hunter… Maybe one who also specializes if explosions and fire … oh right … KRIEG. DLC4
Just a thought