Sales is a tough job, as any manager will tell you. Some startling figures from the book "How to Hire and Develop Your Next Top Performer" highlight this fact. According to authors Herb Greenberg, Harold Weinstein and Patrick Sweeny, approximately 55 percent of people in the sales industry would be better off in another job. Additionally, another 20 to 25 percent of salespeople are selling products they aren't suited to move, which could further hinder results.

In general, sales managers expect the top 20 percent of their workforce to shift 80 percent of their revenue. The fact that 80 percent of their sales force is either barely making quota or failing to meet expectations is a harsh reality to many department heads.

The first thing that may come to mind is a department-wide reorganization. However, this is a drastic step for any company to take, even if a significant portion of the sales team is only barely living up to standards. Before completely rejiggering your sales department, make sure you have given your agents the best possible chance.

So how can managers get the most from their agents? Sales coaching is one possible solution, according to Sales Pro magazine.

In many instances, those who are just meeting quotas aren't bad salespeople, but they haven't received the tools and insight needed to develop the skills to succeed. Similarly, sales managers themselves may not have the leadership skills needed to bring the best out of these middle-tier salespeople.

Before making major changes to sales staff, "you need to design a sales training program – complete with specific scripts – that teach the best practices of your sales process and then properly train your existing team on them," Sales Pro explains. "And finally, you need to teach your managers how to coach and train your reps to adhere to those scripts and best practices. Assuming you take the time to do this first … then you are ready to begin recruiting and hiring more qualified candidates."

Overall, sales departments should be slow to hire and fast to fire. Make sure you have given your sales team the time to develop and fit into the role. However, if these investments aren't paying off, then don't hesitate to fire and keep looking for someone who can fit into that 20 percent.