They didn't say a "competent" developer, they said "their best" developer. They could have some Dilbert-esque metric of "best", the developer who completes their task the fastest, who completes more tasks per time period, etc. Ignore the fact their code generates more followup tasks than anyone else due to omissions, bugs, incompleteness, etc. People will game the system. I have literally seen a coworker introduce a bug and not fix it. With a straight face he explained to me the bug (that they just created) is not on the task list, and that it is OK because QA will find it and create a new task to have it fixed in a future scrum. His manager considered him a role model, the rest of us worked hard to keep a straight face as the manager said this.