I had a great talk tonight with my girlfriend about motivation VS ability. When you or someone you work with produces something that's below average, you've got to ask yourself a simple question: is it a lack of motivation or ability? Is it that you don't want to do it or that you can't do it. Is it that she's not motivated to do it or that she lacks the ability to do it? You can first identify that and then dig deeper and ask why.
It's a good framework to have in your back pocket.