Let's outline what do we usually mean speaking about them:
- top-performers, who stimulates internal competition by their personal example
- leaders, who consolidate and motivate a team
- managers, who build and/or significantly improve processes
- market opinion leaders, who engage attention to the company
- product designers, who architect new awful products
- growth hackers, who make the whole system work better
- specialists with outstanding background, who spread knowledge and best practices
- people with high business and personal ethics, who vitalize the atmosphere
As you see, this way or another an `A-player` is a person who does something on the highest level and adds substantial value for the company growth this way. They are exemplary specialists and personalities whose presence and skills make an influence over the whole team. Their individual contribution works more like a multiplier to the contribution of the rest of the team. In other words, it is a term of cooperation and synergy.
On the other hand, you can't be an `A-player` without a context in a team. You can be a specialist of the highest level and an `A-player` in one team but become seeds of trouble for another. This way, being an `A-player` is nothing more than just a context of a person in a company in a specific moment of time.
In conclusion, an `A-player` is not that a pill working forever once being hired – a person can lose motivation, market insight, or contact with a team. Having said also that a `B-player` can also grow within a team and start driving the whole company.