He was the quarterback coach for the Packers for the last two years. Matt Lafleur was aware that he would not be able to keep him in this position for a while. It was only a matter of time until a team hired him as an offensive coordinator. He was one of the prime candidates for any team in need.
Now the question that remains is how does he fit in Chicago and more importantly, with Justin Fields. Getsy is known for his ability to teach a quarterback how to process his reads as fast as possible. This will be a great asset that Fields can learn, especially if the offensive line is still a little shaky.
Getsy will be able to call some quick passing plays and utilized Fields' legs as much as possible. When your offensive line is struggling a bit, you need to be able to still advance the ball. A great way to do that is with quick passes and screens. Those are often called "the extension of the run game", and for good reasons. The Packers were amazing at that with Devante Adams in the last few years. Hopefully, Getsy will be able to get creative with Darnell Mooney and potentially other weapons he will have on his offense.