I would say they signed him for his experience to help with the 3.5 inexperienced players but yes the goal was never to have him igl (at least initially during the offseason interviews)
They really should've done this much earlier. I am surprised that they weren't using benkai as a second caller from the beginning as it makes sense that benkai should be a signing for his calling rather than his mechanics.
I dont think they had a dedicated secondary before this or if it was indeed blazeking, it could be the reason why his performance was impacted so heavily.