It's really ridiculous since Ground Zeroes is, for all intents and purposes, an epilogue to Peace Walker more than a prologue to MGSV. It brings closure to all the main characters in the game except Kaz and BB, and gives a bit more insight into how
worked in 1974.
Yeah, everything in GZ makes a much more compelling case when viewed from that lense.
For Paz, she went from being a Cipher agent to ultimately, sacrificing herself to prevent the bomb from killing Big Boss. Her emotional 'breakdown' throughout the events of PW of sorts. She went from being a double-agent trust-worthy enough to infiltrate MB, and through the events of PW + your MB efforts that she did what she did in GZ. Her life was a lie, but at the end of life, she chose BB over Zero.
Chico's was a lot less admirable. As someone who's place in the war and conflict was misplaced to begin with, be it his sister/family's revolution till GZ, as a child, he tried to become more than what he was, and the price he paid twice for that was that he betrayed them. He started as a child, was given a chance, but ultimately, didn't grow up as he let his emotions get the better of him.
Same with the downfall of MB. My army of S-rank combatants that all have better stats than Big Boss himself. ;_;