It seems odd that the best salespeople do not make the best sales managers. But that is, unfortunately, the truth.
Empirically speaking, this seems to be a function of “how” those salespeople became great. More often than not, truly great salespeople have some internal “it” that makes them great. They have trouble explaining the “it” to others, and more importantly, they cannot teach “it” to anyone. They just have “it.”
Look at the example of Ted Williams (the last man to bat over .400 in Major League Baseball). When Ted tried his hand at managing a ball team he failed – miserably. Why did he fail? Because he expected everyone to be as naturally gifted as he was. There are debates, but one of the traits that made Ted Williams such a great hitter was that he had extraordinary eyesight. He could see precisely where on the ball he hit each and every pitch. You can’t teach eyesight.
Likewise, a great salesperson cannot teach traits such as a high tolerance for rejection or the ability to read body language. Since they acquired these traits through nature and not nurture, they cannot easily transfer them to someone born with thin skin or a lack of social awareness.
The best sales managers, just like the best baseball managers, come from those who had to work very hard to get where they got. They were generally average or just above average performers, and they watched and learned from the greatest in their game. Because they had to teach themselves to sell (or play baseball), they are best equipped to teach others.