We hired someone once who was only superficially competent in a niche technology that we didn't understand well. This person had a contact with someone who was competent and was coaching them. It took us a while to figure out what was happening. It was a huge PITA because they had to wait for their contact to be available to get anything done.
That's one of the main differences between being "contractor" and "full time employee". As contractor you can sub-contract your work (unless contract clearly specifies otherwise, maybe not enforceable in some jurisdictions?), as employee you can't.
