I agree with you. I've had a similar disappointment with Michael Connolly Bosch series. I first saw the series and actually saw a rerun as well, as although I liked it, one had to really concentrate as there were so many plots going on at the same time. However over the last three months when I started to read books for the first time in years, I started with Connolly, and then realized that the Bosch series consisted of grabbing plots and stories from different books in the series. The books were awesome. I first took a list of Bosch books and started with book one and the further I got, the more I realized what a great disappointment the series really were. I so much prefer the Bosch of the book, and am totally blown away by the writing.
Only sad part is that I'm almost convinced that the last book by Michael Connolly was not written by himself. "The Night Fire". It's almost as though the previous book was used as a template and "The Night Fire" just changed the different stories in it. In these books Bosch teamed up with Renee Ballard. I like his Renee Ballard character, but what a waste of money I thought to have bought the book new. Most of every book by Michael Connolly has its own integrity as being totally different from the next book. That was what I had admired most about this guy, up and until his last novel.
And so it goes. While I was moaning to my brother in law about this, he had had an exact experience with a similar great action author, Lee Child. He is convinced his last novel was written by a ghost writer. So I guess in book form it almost becomes the equivalent of the movies where when the going is good the author allows his publisher to go with a ghost writer. That's what I think in any way had happened with "The Night Fire". Michael Connolly is now into mass production and for me that is loss of integrity. Not sure I'll be reading any of his next books until they are old enough and available in a second hand book shop.
Bottom line. I'm not so sure that your series will be the same as the book, but if it is like the Jesse Stone series with Tom Selleck, then who knows, maybe it can be OK. I thought the Jesse Stone series were very different from the book, but at the same time had an integrity of its own. So at least we know that if you have a really good director and producer, there is a chance that the series will be OK, but may never really be an exact replica of the book.