I have the highest standards for my staff members; as they represent everything about the community. If they are not active, members won't be as active as some members love certain staff members and only post when they see them. If my staff members are not happy jumping jelly beans, it might affect the members in a negative way.
For me it's not how many posts they make, however they do have to post every day, but it's the quality of those posts and what those posts bring to the community. If you sound like a emotionless robot without any kind of happy or even sad tone in your posts, and you're on my staff team, you're going to get the boot unless you have a good reason to be so down. Granted, everyone needs a break, so if my staff start to get tired of posting and what not, I simply tell them to take a break and they come back like they were hit with bolts of energy.
It's pretty hard getting onto my staff team, and super easy to get off of it. All my staff are required to login every day, (because let's be honest, it takes literally 3 seconds) and unless they have somewhere to be or a situation at home, they are required to post at least 50 posts a week.
Now on my forum, we don't "delete" posts and message them saying why or to knock their shenanigans off, instead we post in the thread and lock it, or simply reply to their post if it's not their thread. So in all actuality, they should rack up more than 50 posts if they moderator and interact with the community. My staff are set to probably ridiculously high standards, but then again I only hire those who I know can meet those standards.