You get a call from a company that's considering hiring one of your ex-coworkers. They want to know if you would recommend him for this new job. This ex-coworker was very opinionated and hard to work with, so you say this about him.
He's not exactly what you'd call a "team player".
This is an example of understatement. If you're talking about someone and say:
She's not exactly poor.
...it means that she actually has a lot of money. Instead of simply saying "She's rich", you might use this expression in order to sound witty and intelligent.
Here's another example: if your husband is overweight, but made fun of you for being a little heavy, you can say:
You're not exactly in the best shape yourself, you know.
"Not exactly" can be followed either by an adjective, or by a noun:
A: You're dumb.
B: You're not exactly a rocket scientist yourself.
In business, a "team player" is someone who is helpful and easy to get along with. A person who disagrees with people a lot, or who doesn't listen to other people's ideas, is not a "team player".
When a speaker calls someone a "team player", it's usually meant as a positive description.
"Not what you'd call ___" means "not exactly ___" or "not really ___".
This expression is used for understatement. Instead of directly describing something in an extreme way, you introduce your description with "not what you'd call ___". For example, if you're a very bad dancer, you can say:
I'm not what you'd call a great dancer.
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