Any predictions I make about this year's Man Booker prize longlist, which is announced on Wednesday, will most likely be wrong. Even before I was a judge in 2013, I realised that one should probably judge the judges, not the novels, if one were planning a trip to the turf accountant's. That explained my singular failure to predict a winner – my intellectual bitcoins were on Will Self not Hilary Mantel in 2012, Tom McCarthy not Howard Jacobson in 2010, and indeed, had I been alive in 1969 for the first Booker, I'd have gone for Muriel Spark, GM Williams, Iris Murdoch or Nicholas Mosley over PH Newby. The rare year when the book I thought should win did win – Eleanor Catton's The Luminaries - was when I was a judge. It's especially difficult to cast the runes this year, as The Rules Have Changed, which is usually translated into The Americans Are Coming, usually with an exclamation mark. It's not only a wider field for the judges to choose from, but the judging panel has been increased to six (a mistake in my view, giving a casting vote to the chair), and the number of books publishers can submit has been altered to a sliding scale, dependent on their previous success at what the 2011 winner Julian Barnes once called "posh bingo".

That said, there are some things we do know. Previous winners get a free pass to the judges' attention – so Ian McEwan's The Children Act and Howard Jacobson's J will both have been considered. Given McEwan's novel is about a female judge dealing with a religious young man who wants to opt out of life-saving medical treatment, it will perhaps strike a chord with the chair, the vocal atheist and philosopher, AC Grayling. Jacobson's novel is set in the future, where certain words are self-censored: quite a change from his earlier comedic work, and speculative fiction doesn't have the best track record at the Man Booker. I've read neither book, but, on their past performances, would happily see neither on the longlist.

Other big names have obviously been read and pondered over. I'd hope that Will Self's Shark, David Mitchell's The Bone Clocks, Nicola Barker's In The Approaches and Ali Smith's How To Be Both were given critical scrutiny and vigorous debate. No doubt Martin Amis, the doyen of not-winning-the-Booker, was considered for his Holocaust romance, The Zone of Interest. I'd be surprised if Alan Warner's Their Lips Talk Of Mischief wasn't in the running, and equally surprised if Irvine Welsh's The Sex Life Of Siamese Twins were. Philip Hensher's Cloud Atlas-y The Emperor Waltz and Neel Mukherjee's The Lives Of Others would be worth a punt on review coverage alone. The judges will have had to trudge through the usual bilge and no-hopers – my only regret at being a Man Booker judge was how much drivel I assiduously read that year – and they will have found gems that the wider reading public, even the literati, didn't catch. I hope there's an equivalent to NoViolet Bulawayo or Richard House on their longlist. I'm hopeful about this year's Man Booker because Erica Wagner, the former literary editor of the Times, is there. She previously was on the panel that surprised everyone with Life Of Pi, and I can't but imagine that she will push through at least one book of awkward excellence.

But the question is: which American writer will make it through? The novels that impressed me most this year were Jonathan Lethem's Dissident Gardens, Mark Z Danielewski's The Fifty Year Sword (which may be ineligible given its vagrant publication record) and Jeff VanderMeer's Southern Reach trilogy, all three interlinked novels published within this year. Were they submitted? We will never know. Donna Tartt's (to my mind, rather bloated) The Goldfinch? Having already won prizes, it might be stymied by success. I predict that the Americans will make only three of the 12 or 13 longlist spots. If I'm wrong, I hope I'm wrong because the judges found something remarkable. I'd love to see some outliers in there: Nnedi Okorafor's Lagoon, Broken Monsters by Lauren Beukes, or even a graphic novel (I'd have chosen Mike Carey's Tommy Taylor And The Boat That Sank Twice).

The best thing about the Man Booker from the outside is the capacity to surprise. I cross my fingers it does so on Wednesday.