Originally Posted by Soiyeruda
Zephyr is more of a Phantom Dancer contender than it is a general AD champion item. You'll pick Zephyr over Phantom Dancer if you want generally better stats (and tenacity, which is a huge bonus) and you'll pick Phantom Dancer if you want the higher crit rate.
Im sorry but, which adc would preffer zephyr over pd?
Thats right, none. You cant simply give up the crit on the PD for a little CDR/tenacity, this item can work on some bruisers but if it was designed to be one of the pd replacement options then it definitely failed its job.
You can say that Shiv is a choice to replace PD, but it gives overall less stats for the passive proc, which is something that most of carries could care less as they need the most item slot efficiency they can get.