What qualifies an employee to be a middle level manager?

authority. management positions come with authority. if you can exercise authority and make decisions then you are technically considered a manager. i just learned this my self. for example, if you have the authority to exercise performance review of staff and make decisions on who gets how much increase in pay, you are exercising authority. another example is if you are working with a vendor and you decide on behalf of the company that this vendor should be replaced with a different vendor, again, you have exercised management authority.