Yes he has made great strides over the preseason, but he needs to show top form consistently in the VFL first as he's been predominantly been a VFL reserves player so far in his career. Amos has had a good preseason, but that doesn't mean he should be rewarded with a game.
As for the special mention, that mention came after Clarko was questioned about Grimley.
Grimley's got promise, but one good practice match does not make a player of his experience worthy of AFL games.
I haven't heard the Kangaroo presser but following the Richmond game it was Clarko that brought Sam's name up. Clarkson was asked after the Richmond game about Hill ... " he's had a pretty good summer, Grimley's had a pretty good summer and Wanganeen and young Anderson " - He's been pleased with his progression and whatever thoughts we all had about Grimley 2012, Grimley 2013 is a big improver and is obviously a lot closer to AFL consideration.
I disagree that it is a prerequisite for an AFL game that you must show consistency at a lower level before promotion or you must be perceived by your peers and supporters as deserving of a spot because you have been consistent on game day at the VFL or VFL reserves level.
It's about playing your role for the team.
You could argue that from the VFL games we saw that Schneider earned his stripes -- but the club didn't have a role for him. Breust played some shocking games at VFL level just prior to being picked for the seniors as did Suckling yet they were picked because the coaching staff believed they could play their roles - and they have.
If Amos Frank and Sam Grimley have had good preseasons and we have holes in our senior playing team and the coaching staff feel that they have the attributes to make a contribution at AFL level in the role they assign to them then why shouldn't they be rewarded with a game despite little VFL experience.
And the NAB cup is about exposing the young players to a higher level and seeing how they respond. Grimley has responded well. If the coaches believe he is in better form than Bailey and can perform the role they have assigned to him better than Bailey then he should play - even against the 'terrifying Cats' - and even though Bailey has more experience.