Aside from your GPA, MCAT, application, personal statement, etc, etc, your secondaries are very important.
Pretty much every step in the whole process is important, which makes me wonder why people alwasy stress GPA and MCAT...however, everything you do is pretty important. If you have an excellent GPA and MCAT, but write to save your life, then you better fix that situation. Each step in the process is an evaluation of your whole self, all of it needs to be top notch.....but it also all has to be in early.