McCartin reminds me a bit of Jack Darling in both looks and attitude. Both are strong, aggressive at the man and ball and have good hands. Neither seem to possess a backward step.
Obviously it is difficult to know if Paddy can step straight up into an AFL side. By the sounds of it he will need to work hard on his endurance running but Roos proved last year with JKH that he will promote first year players into the side despite preferring they serve apprenticeships at a lower level.
If Paddy can have an uninterrupted pre-season then I think he could surprise and play half a dozen or so games.
By the way, Darling played 23 in his first season