That pretty much sums up my response. In addition, Biden needs more coaching on how to respond when Trump interrupts and goads him. Last night, every time Trump talked over him, Biden stopped speaking, so it was hard for him to string together a full sentence and say anything of substance.
What he did wrong was he would stop and address everything Trump said to him. Therefore causing Trump to become the moderator. What you should have done is stopped what he was saying, look straight ahead at the camera, and wait till Trump finished. And then just start again picking up.