Simmering down somewhat from the suggestion of Jake coaching us, here's how I see it (and therefore, pretty much how it is):
Jakeball allowed the Brumbies to turn around their shitty situation very well. It required good kickers, high levels of fitness and defense, and a technically excellent forward pack with its head screwed on at set piece time.
It still allows for freedom of expression in good players, but for a longer tournament like Super Rugby, its very difficult to sustain because of the attrition rate you're bound to encounter. The Brumbies showed that when it came down to the crunch, they weren't good enough to pull off the last win, either through inexperience against the Reds in 2012 or through fatigue - aggravated by the travel from South Africa to beat the Bulls.
It helped that the Brumbies had what Jakeball needs in terms of backs - a few guys with big boots, big units who can make gain line, and some wingers with a bit of toe.
The key things in both years was that Jakeball didn't deliver the Brumbies a top 2 spot, in a game plan that ultimately asks you to win every game by 1 point as a minimum. This is a key thing, as its not like they were short on talent.
Jakeball COULD work in a short tournament like RWC, where the attrition isn't such a big factor, but if your forwards can't dominate, you're not going to get a lot of change out of it.
Laurie Fisher is gone of course, which is the real shame.