Do you recall some of your college professors who knew their subject matter but had zero teaching skills? Staying awake in their one-way-directed lecture classes required Herculean strength (or lots of coffee). They were never trained to develop the skillset of engagement strategies.
Even though I was a physician with a strong science background, when I decided to become a classroom teacher (and thought I’d teach science), I did not want to make that career change without the benefit of instruction and guided student teaching. The year I spent in my graduate school of education program was invaluable in my transition to becoming a professional educator.