Commission based Sales is rough, always a revolving door. It's a cultural thing. I have been in B2B Sales for 11 years now and worked in 6 places total. I've been in MCA for just over 10 months and having interviewed at a few places noticed it is not much of an interview. They give you a tiny bit of rah-rah company BS, ask a couple of quick questions, discuss compensation and ask when you can start(from the small sample size I've seen and stories I have heard at least).

From my experience if you make someone go through an actual interview process: Phone screen, 1st face-to-face, follow-up, maybe a mock pitch, or some type of basic test to see if a Candidate is a fit, then a Final Interview it makes it more important to them and weeds out the people you don't want. Follow that up with a few days of hands on training(and continued Sales and Product training afterwards) you create a winning culture. Those that don't micromanage but coach their Sales staff and rewards them for production are often the ones that see the least amount of turnaround. Those that bring someone in and say "Come in Monday at 9:00" without interviewing them, don't train them, omit important details about compensation, and just put them in front of a phone without any development are the ones that are and always will be revolving doors.