Just an aside to this, it’s not necessarily poor play but the environment changing dramatically between key levels. Specs doing 20s that have long ramp up / require long setups will typically underperform compared to plug and play burst DPS (Mostly melee) but once things start living they can spread their wings. The best SPs / Moonkins, despite being able to hold their own against the average quality of player doing 20s, will be absolute shadows of what they might be capable of at higher key levels.
Not to say there’s an obvious answer to this, but wanting to feel strong in the content level you do isn’t always just a case of “Play better”.