Royal Marine has never done anything to suggest hes anywhere near winning a Guineas, Advertise is a sprinter and it might be a bit of a culture shock for Skardu after only running in a moderately run G3 trial. Great Scot is a live outsider, can see him running well.
I think the right horses are the top 3 in the betting, if Ten Sovereigns stays he wins, same comments would have applied to Calyx who is a class above this field in terms of ability and elite acceleration, a real shame they ran him in an egg and spoon trial instead.
Madhmoon has a better case than most, he was among the top prospects last year and conditions look ideal for him, but he always looked just below the best when compared to Ten Sovereigns, Quorto, Too Darn Hot and Calyx. Given that only Ten Sovereigns made it to the race, he has become one of the main players by default, his comeback run was solid but not spectacular and I think one of the Ballydoyle runners might be too good for him.
Magna Grecia done well to go from a maiden to a G1 win in the space of a month, running the best French colt Persian King close in between. Thats pretty high level form in the context of this race and with proven stamina, the market had him favourite until it was revealed that Moore was riding Ten Sovereigns.
Its a sore head with Ballydoyle in these classics and only they will know the true situation, whatever Moore rode would have been favourite and hes been on the wrong one on many occasions in recent years so its probably best to ignore the recent odds changes. Magna Grecia and Ten Sovereigns have run 6 times between them and Donnacha has been on for 5 of those, he knows the horses better than Moore and Obrien obviously gives his sons a few classics before they retire, could they have nudged Moore in the wrong direction? I think at the odds now and with proven stamina Magna Grecia is the right call, especially if he stays solid in the betting on the day, but im far from confident, I would have been very strong on Calyx and the race is just giving me a sore head now.