It's not your manager you're impressing here, it's your coworkers. Companies get backchannel references from people who've worked with you, if they're at the co

It's not your manager you're impressing here, it's your coworkers. Companies get backchannel references from people who've worked with you, if they're at the company you're applying to. An extreme case is Google, who'll ask anyone and everyone in the company who have an intersection in resumes with you. Also, easiest way to get another job is for an ex-coworker to recommend you. Keep those bridges built.