There's something very deer-in-the-headlights about watching senior NBN Co executives front up to a Senate committee to explain their progress — and I use that word in its loosest meaning — in converting the National Broadband Network (NBN) from something ambitious yet imperfect into a leap of faith that should more appropriately be called imaginary and imprecise.

One almost felt a pang of sympathy for the three visibly uncomfortable NBN Co executives who fronted up to the usual grilling — about the plan they have been charged with executing against logic, common sense, and commercial reality — with the usual cadre of difficult concessions, incomplete answers, and deferrals to put questions on notice. Grab some popcorn, and watch the session for yourself.

To their credit, they did try hard to give good answers, but a face-palming moment came when Senator Scott Ludlam's questioning led the NBN Co executives to admit that despite more than a year and a half of rhetoric and policy shifts, NBN Co still has not laid a single hand on any part of the hybrid fibre-coaxial (HFC) networks of Telstra or Optus, not even on a trial basis.

Given that the networks are supposed to account for over a quarter of all NBN connections by the time the network is done, you'd think they might have tried a bit harder to make that happen. But no; negotiations are still under way, and until they're completed, everything you've heard about the HFC-based NBN, even from technical experts speaking in the realm of the hypothetical , is still complete and utter speculation.

In other words, more than half of the multi-technology mix (MTM) NBN is still entirely imaginary, existing only in the rarefied thought bubble in which the current government's NBN plans are continuing to evolve. NBN Co's management may think it is scoring points with what has become an institutionalised, rabid, and jargonistic promotion of the new MTM, but when pressed to explain what's happening, it is still woefully short on answers.

Nowhere was this more obvious than in the Corporate Plan 2014-17, released this week.

At 60 pages, this long-awaited plan is not only one-third the size of the last corporate plan prepared by NBN Co — version 13, a long-hidden revision whose contents were revealed by ZDNet this week — but it is as long on vision as it is short on detail from the beginning to the end. Its pages are filled with supposition, tired rehashing of statements about what broadband really means, and more qualifiers than you would expect from a groom trying to explain to his bride why his buck's night got out of hand.

Nowhere in recent memory has a major policy document been filled with so many warnings that we should not and cannot believe most of what it contains.

More than half of the MTM NBN is still entirely imaginary, existing only in the rarefied thought bubble in which the current government's NBN plans are continuing to evolve.

After three years in opposition and almost 15 months as communications minister, all that Malcolm Turnbull's ministry has been able to create is a sorely overstressed NBN Co; a recipe for massive infrastructure change that is still missing half of its ingredients; a series of questionable procedural reviews set up from the beginning to deliver the desired result; and a corporate plan that leaves everything to the imagination.

If you haven't read the new corporate plan, I encourage you to download it and scroll to page 45, where NBN Co has been kind enough to categorise the 28 different major assumptions it has made in creating rollout and financial projections that paint a pallid and uninspiring future of Australia's broadband — at nearly the same cost as the previous all-fibre model.

Yes, 28 major assumptions. That's more than twice the number of discrete challenges NBN Co identified last year as potentially impeding the transition to a fibre-to-the-node (FttN) model. In other words, after more than a year of getting to understand the Coalition's broadband plan better, NBN Co now argues that it is more than twice as complicated as it feared when it was just an election-time sound bite.

NBN Co may call it conservative prudence, but voters who just want better broadband would be well justified in calling the whole exercise a con job of the highest order — especially when faced with revelations that the former NBN Co board may actually have known what it was doing before it was unceremoniously pushed off the proverbial cliff by incoming minister Turnbull.

Just days before, after all, NBN Co had finalised draft 13 of its Corporate Plan 2013-16, which adjusted the rollout timeframe and incorporated a range of savings measures that were intended to reflect the benefits of new technical architectures that had been developed, as such things are, through repeated iterations of trial and error.

Sure, its NBN wasn't perfect, but the process was always going to be a learning process. Former CEO Mike Quigley promised in the dying days of the Labor government that the company — mindful even then, despite the Coalition's political characterisations of Labor's NBN as spendthrift geeks — had figured out how to pull considerable costs out of the project, and would continue to do so.

Quigley was not lying when he said that the project was just about to start getting much better.

The version 13 corporate plan reflected this reality, and in retrospect, its forecasts weren't so far from what the Turnbull-led NBN Co has actually achieved so far. Just imagine what NBN Co could have achieved had it not been sidelined by the transition to the new model.

What has been most interesting, however, is NBN Co's characterisation of its trial of new rollout techniques in Melton, Victoria; it dedicated an entire web page to a long-winded denial that the Melton work proved that the changes outlined and costed out in v13 had paid off.

The obvious questions — such as how NBN Co senior management could possibly be unaware of such a trial being conducted in their own organisation; why the company was so quick to dismiss reports that it was doing its job better than it has done previously; and why Turnbull's office initially reacted with open hostility to the findings — are less important than the fact that the Melton results prove that NBN Co is in fact doing exactly what it is supposed to do: Figure out ways to do its job better.

Say what you will about the Labor government, but the structure of v13 — indeed, its very existence — shows that the people responsible for delivering its NBN vision were indeed doing their best to keep its costs and delivery under control. Quigley was not lying when he said that the project was just about to start getting much better. And while v13 may well be, as NBN Co put it, an "historical curiosity" at this point, it and the Melton results are a reminder that everything we're being told about the current MTM needs to be taken with many grains of salt.

One feels for the current NBN Co executives, who are trying to make headway despite the challenges posed by the hapless MTM mission statement they are now supposed to execute. This is why they look so uncomfortable in their hearings; they have no real answers to give, no progress to report about MTM other than that they are working on it.

They are doing their best in difficult circumstances, but the preponderance of non-answers and pained expressions amongst the assembled NBN Co executives confirm what is obvious to anybody watching this week's Estimates hearing or reading the Corporate Plan 2014-15. And that, of course, is that the current government is still a long, long, long, long way from being able to say what the future NBN will look like.