Another related question is how would you evaluate the quality of hires? So you hire for a team of 5 people who complete 83% of the tasks you set for them that

Another related question is how would you evaluate the quality of hires? So you hire for a team of 5 people who complete 83% of the tasks you set for them that year. How do you know if you hired well? Is this an excellent result or a terrible one? How do you know how well each of those 5 did and how well the team would have done with other people in the roles?