Not sure what game some people were watching but other defenders playing poor (which overall, they all did well- including Adriano except for being beat for the header on the goal) doesn't really have anything to do with Bartra's performance.
Bartra was fantastic- plain and simple. This is coming from someone who absolutely did not believe in him in the recent past. He's impressed me, especially last game. He showed pace that I never knew he had; possibly because he's never really used it before. He played with confidence, chased down attackers on a few occasions and read the game tackling/intercepting a few balls using his pace. I enjoyed that greatly because that's exactly what we need. He's skinny but 6'0 and only 22, if he's naturally strong/tough he could be what we need.
I wont get too excited but I hope we continue to play him, and a lot. If he continues to show quality and improves, we might not need to buy a CB in the end.