Any generic wordpress developer may know wordpress very well but will have to spend a good amount of time to know AVADA code and features.[And note as a client this will be in your billable time or else the developer will be underpaid affecting the quality of work].Though AVADA is a wordpress theme, over a period of timeline with its HUGE userbase it has evolved to be a framework in its own way. Its code is not generic wordpress code and AVADA has its own coding style and architecture. This is same as a car mechanic may know the generic working and architecture of cars but if he has not worked on an Audi or Ferrari then he will need to spend a good amount of time learning Audi or Ferrari specifics.
However our team members are not only experts in wordpress but work ONLY on AVADA and know it inside out. And just like an Audi or Ferrari specialist mechanic would know all specifics of finetuning and working on Audi or Ferrari, Our team members know each line of code in AVADA(and for us AVADA is Audi or Ferrari of wordpress:)). Though there are more reasons to use our team but just this one reason saves you hundreds of hours because of:-