Which Is More Important? Do the Work or Speak the Work?

With more and more years of work experience, I am starting to ask myself the question of whether it is important to do the work or speak the work? 

Since I was little and when at school, I always believe that doing the work and doing it wholeheartedly is what gets me to the next level.  However, since I have started working and over the years, I begin to see that those who get the fastest promotion and advancements are the ones who know how to speak well and give good impression. It is almost that once you know how to present yourself and your work well, that already makes up most of what matters.  Maybe work is about impression and communication more than anything else, what are your thoughts?

Joanna