Success as measured by time

I recently read an article on HBR.ORG titled "Stop Working All Those Hours" and it has really made to stop and think about how people, myself included, measure success. The general premise here is that success in the workplace is often measured by the amount of time spent in the office. Stop and think about this for a moment; is it true?
Will spending 50+ hours a week in the office really make you a better employee? Or is it a perfect demonstration of not being as efficient as you could be? Metrics are an important factor in a business, I mean you have to have some empirical data by which you compare employees against each other. But is hours worked a valid metric? Does the employee that came in on Saturday deserve recognition if they could have completed the task on Friday? Is the employee that leaves early to watch their childrens' little league game less dedicated to his or her job?