Just before the first Lions test I was talking with some Welshmen. One item that greatly interested me was their assertion that the Australian front rowers looked unfit and overweight. They singled out Fatcat for special attention. They were not ranting or being provincial or talking up their own boys. This was a quiet, serious Rugby discussion with some blokes who obviously lived for the game and were very knowledgeable. It was prompted by my query on how they thought our scrum would stand up.
I have to say I agreed with them on that point and if you look back on my posts from a couple of years ago you will see me questioning why many of our front rowers (not all) looked to be carrying weight around their middle, and when shirtless they showed little abdominal definition, which is in direct contrast to other top level props around the world, even grandfather Castrogiovani was more trim. Now other props, even Maafu have dropped much weight, but this year I thought Fatcat was as big or even bigger than ever. Perhaps it is purely a fitness issue. I doubt that anybody could say it was a skill issue or even really a form issue, though I would suggest he has been up and down. Link has said outright that Fatcat knows what he has to do to get back into the squad and he is still in the frame. SO given there is no Super Rugby, the club season is almost done and he isn't in the test squad, I do think it is purely a fitness issue.
In any event I think that Sio was in better form than Robinson and more consistently so, especially in the big games at the end of the season. So if Sio makes the match day 23 I would suggest it is starting with possibly Anae and one of Kepu/Alexander/Slipper also starting and another on the bench.
My starting and reserve front row would be:-
1.Sio
2. Moore
3. Slipper/Kepu
16. Fainga'a
17. Anae/Alexander (I would prefer Anae I think at LH)
18. Kepu/Slipper