I wanted to add to this.
You have to define shy. Shy in a social situation or shy as in too nervous to talk to your patients?? Most people know how to do their job, they just don't tend to be talkative in social situations out of work because the phony and insincere nature of people in social settings. And actually I suppose I'd agree with Panda and say the proper term to describe the aforementioned is RESERVED NOT SHY!
Most physicians I know are reserved. Does it make them bad physicians? NO! Being a physician is just like any other job in life in one sense. You are reserved only in particular situations not in every situation in life. I'm sure these same people know how to diplomatically and politely talk with their patients and if they don't they LEARN to do so.