Actually Human Error as a percentage of accident causes has stayed pretty constant between 45-56% since the 1940s.
Technology hasn't necessarily mitigated it, all it has done is change the way we as humans manage to d##k things up in the cockpit. The big risk in this scenario is the way we are trained to fly. The emphasis is no longer on the basics, but more towards systems management. Raw data hand flying could be trained to extreme proficiency in newhire, upgrade and recurrent simulator curricula. But that adds to the training footprint, and most airlines simply don't want to pay the extra cost. Kind of scary really. All we can do is try to hand fly to the extent that company policy and workload allows, so that days like this don't put an airline crew out of the "comfort zone".