You mean Irving is a poor defender. Shocking.
In all seriousness, this shows one of the fundamental problems when you have a player that does so much offensively. They just don't have the energy to consistently perform at a high level defensively. That isn't to say Irving will ever be a + defender, as he won't, but for stretches when he applies himself he can at least be passable defensively. He just can't do that and bring the offensive intensity except for short periods of time. It happens with all great players, they just can't keep bringing it night in and night out on both ends of the floor. It is just too draining. As long as Irving is outperforming his counterpart by a good enough margin, his poor defense just doesn't matter in the scheme of things.