Firstly, well said Brumbieman 100% agree. My thought exactly.
The point i was trying to make with Pat McCabe is that if he was slotted into 12 it would mean changing our whole back-line structure/game plan. We go from playing 2 playmakers at 10,12 to having one playmaker and a direct runner in McCabe. (if To'omua was at 10 id imagine a pretty predictable back-line) I don't think it is a good idea to change game plans with every injury - I like the all blacks style where they slot in players who fit the game plan. I'd prefer Colman at 12 if either To'omua or Leali get injured.
Well, that IMO depends on the 10. With Lealiifano there, McCabe was our 12 in 2012 and they carved up, because McCabe did exactly what To'omua is doing now, what Fainga'a does for the Reds/Wallabies and what Nathan Grey did 10 years ago, what Nonu does primarily (his new found kicking and passing is just a bonus) for NZ, what Tim Horan did as well:
Provide a hard, and direct running option to provide go forward and straighten the attack so that the 13 an doutside backs have space, and then eat anyone who runs into his channel for dinner in defence.
Lealiifano is the more creative passing/running, flashy 10 that makes the hard 12 really shine. To'omua is a bit more Johnny Wilkinson than Spencer, so he needs a playmaking 12 to up the unpredictability level, and then you need a big physical 13 to straighten, eg Kuridrani/Mortlock.
Lealiifano-To'omua-Kuridrani is a hell of a midfield, as you have the creativity of Lilo, To'omua giving the directness (but still able to sell a dummy or run a phase or two if the 10 is under a ruck) at 12 that is giving Kuridrani space at 13 to cause havoc. Add in Tomane, Speight and Mogg running support lines off his shoulder, and that would be a freaking nightmare to defend against, let alone attack, with the whole midfield being aggressive defenders.
With To'omua at 10, the balance isn't quite right IMO, as you're sort of relying on the creativity to come from 12, where it's a bit harder because the team is really needing go-forward there, not dancing. The 2nd flyhalf system just puts pressure on the 13 as they normally have less space and need to be bigger to get any go-forward.
Roffschoice: I agree, Bernie knows his shit, but i'm just curious as to whether things have changed with To'omua's form at 12. Thy had him at 10 because he wasn't seen to be as adaptable as Lealiifano, but with him now carving up and really playing better than i've ever seen him play, I wonder/hope that it solves the riddle of how you fit two flyhalves into a backline, and lets them play Lealiifano as a flyhalf now that To'omua has shown he carves up more at 12.