The previous sentence is affirmative. The last sentence is not. Just because a person's thesis is not well written does not mean that his professional ability is not good. Secretarial students may not be able to write decent official documents. If you write too much, even if you are a science and engineering major, you can still write papers with clear logic and full of thoughts. Besides, I don't know what you mean by professional ability. Are you engaged in writing or other industries that have nothing to do with writing? If it is the former, it will be better to write more, which is really related to your professional ability. The latter case has something to do with the topic you choose and your writing and expression ability, and has nothing to do with your professional ability.