Hi there,
There is something i really dont understand and ill need you to help me.
Well im a lightweight cat B rider (1m68, 53kg) my FTP is 225w (so i guess 4.23w per kilos).
I have no problem in flat races (Nevers win but few top 3 and some good places) but i tried 4 Times races with Big climbs like Alpes or Ventoux and i go beaten by a lot of riders in my cat and even cat C with a really lower watts/kg. I dont understand… Is it not suppose to be easier for me to climb racing ? Is pure wattage the only truth in Zwift ? I was scared because in Real life im climbing pretty good and now i feel like ive Lost everything.
Thx 
IRL, I am like you, only a bit heavier and a bit lower FTP. And both IRL and in Zwift, I am not as good on extended climbs. My anaerobic power is better than my aerobic power, so I am good in a sprint or a 1-3 minute effort, provided I can stay with the front group and be in a position to put that sort of effort in. I wonder if you are in the same boat.
Basically, FTP is only one measure of cycling power. You also need to consider someone’s power at VO2max, I.e. 3-8 minutes, their anaerobic power at 1-3 minutes, their power in a sprint. Depending on your needs, you might want to focus on your VO2max and FTP. I don’t road race anymore, so most of my training for cycling on the road is that type of effort.