This, grabbed from the article, is right on:
“When you’re in the flow and you’re not thinking about it, you just bowl and you just trust your skills.” Of that day at Lord’s, Boswell said: “I just didn’t trust myself. I didn’t trust my action and I didn’t trust my skill set, and then when it was put under high pressure, it failed.”
When athletes are anxious, they overthink, and focus attention on the technical execution of the skill – those aspects of the movement that have generally become automated. It has been called “paralysis by analysis”: the mental effort actually inhibits performance. This explains why Boswell, a 26-year-old in his seventh season as a professional cricketer, suddenly found himself unable to bowl straight.