Can the ability to speak and listen effectively can mean the difference between succeeding and failing in a job?

The difference:

To speak and listen effectively;

If you speak effectively then others will understand what your saying and thier able to carry out with the details, If you listen effectively, then your able to understand what is being said to you and your able to carry out the details.

The difference between succeeding and failing in a job

If you dont listen effectively then your unable to understand what the point is their trying to make and if you cannot understand the point, then your not able to do what is being asked, to their specifications.