The best way to avoid ignoring B players with potential is to throw out your preconceived notions of each employee and reassess them from an unbiased angle. Do you have one employee who has the right skills but maybe lacks interpersonal communication skills at work? Or maybe you have an employee who is the opposite, and they're great at working with others, but sometimes lack the right skills and know-how to get the job done. Figure out suggestions to improve upon these aspects of their career before you talk to them. And then, be honest with them, even if it's uncomfortable.
Don't go back to high school
"You want to stay away from viewing your department as the high school lunch table. You don't want people to not be able to move from one section of hierarchy to another based purely on perception and the only way to do that is to engage with them," says Gimbel. "People want open candid feedback. They want to know where they have to improve; what makes good middle managers good is that they actually have frank honest conversations with people."
When talking with employees about what they do - or don't - bring to the table, remember to frame it in a positive way. Tell them you think they are close to becoming a corporate star, but that they simply need to focus on a few skills or traits. Emphasize what they're doing right, and be supportive about what they need to work on. And remember to give them actionable ways to improve on their work, and motivation to do so, rather than just leaving them to figure it out alone. You might be surprised how many of your B players rise up to A players with just a little motivation, which will only make your job easier.
Gimbel says middle management is hard, and you need to be prepared for the unexpected nature of dealing with different personality types. But ultimately, he says, "the goal is to figure out a way to get people who are really good to rise up, and the [best] way is to make sure you're spending your attention in the right places."