It's strange that so many people seem to think they know they're doing fine on a DD job without actually having seen a single parse of themselves. The truth is, you can not know. There is more to playing a DD job than reading up on the optimal rotation (that someone else has parsed, mind you) and then trying to copy it. It's also, for example, about small differences between two DDs doing the same rotation but handling mechanics a bit differently, and even things such as how they push their buttons (do they queue all their abilities). Without a parser, looking at two DDs who seem to be doing the same things in same order doesn't tell anyone anything about their actual damage, and there can be a huge difference between the two. Simply knowing the optimal rotation does not make anyone a good DD in practice.