Jack of All Trades, Master of None?

I found the article posted by my classmate Too Many Teachers Can't Do Math, Let Alone Teach It to be very interesting and so I decided to express my concerns and opinions on the subject here. In brief, the article expresses growing concerns with the lack of educating educators in math and how unprepared teachers are in the classroom to teach young students the subject.

I think this article pertains a great deal to the idea of teachers being “jack of all trades, master of none”. And although I did enjoy my undergrad program, I do not feel it fully prepared me for a number of different aspects of the teaching profession. There are such a number of subjects, and a specific number of outcomes per grade per subject. Besides the facts/information presented in each subject, teachers also must juggle many day to day routines- organization, preparation for lessons, along with maintaining an environment which promotes fair and equal opportunities for all, social justice and much more. I am just wondering how and where teachers are expected to get the detailed training for all aspects of this career within their university education?

This being said, one of the biggest points we are taught in our teaching education is to “be prepared for the unexpected”. How can one prepare for the unknown?
Also, quite often, teachers are offered positions in an unfamiliar territory- weather it be in an unexpected grade level, a specialized subject area, or in a multigrade/age classroom. Teachers are expected to adapt to their environment and prevail while

Yes I do agree that in order for teachers to successfully teach students, an established level of familiarization with the information at hand must be established. But are teachers expected to know everything about everything at all times? I think the most we can do is prepare for the unexpected and really make the extra effort in learning it ourselves before we teach.