Let's say that you are in an elevator but don't know what floor the elevator is on. If you stick your hand out at waist level. How high is your had above ground level? Without knowing where your ground reference is on the display is, you know as much about the displayed waveform.
When you set the scope, you need to use DC coupling and you should set the ground as the center reference line. That's now the following scope was set up. You can see that the waveform is going to within a volt of ground. That's something that's critical to know when viewing drive waveforms.