Cycling is predominantly an aerobic sport (fitness based) biomechanics do play a role, but often once you adapt to any position, provided it's not too extreme it's your engine which holds you back.
Polarisation works in cycling in some athletes by stimulating the aerobic system, through overtaxing all elements of oxygen provision and energy production (HIIT). Combing this with a large amount of low end work which works in part on efficiency of movement on a muscular level and to some degree structural changes (although the extent to which this happens over a certain age is a little debatable)
The threshold model, seems to be more related to the metabolic side of things, working on mitochondria (cell energy power stations) amongst other things to increase the ability to produce energy and maintain contraction of muscle fibres.
So what's the difference with running? Running is a very very different activity. Yes it does involve and require a great aerobic engine to supply oxygen, and yes it requires the need for lots of well functioning mitochondria to provide energy, but biomechanics start to play a much greater role.
Partly because you are free form, not fixed to pedals etc. So how you move and land etc. Becomes important. But mostly because in runnnig you 're-use' some of the impact energy by using your tendon complexes as a spring type system.
There is also the control element, I.e. Neuromuscular control, as the movements are so fast, require incredible balance and proprioception, that training this element is crucial.
So polarisation of running (which is essential imho) involves long easy running (combined with ballistic movements such as plyometrics) which works on tendon and soft tissue structure and stiffness. This allows greater recoil ability (whilst building the aerobic engine at the same time of course), combining this with very very fast short reps on treadmill or track ideally which focus on training the neuromuscular system to balance, control and use that recoil.
Hence why running polarisation is very different from aerobic type cycling polarisation.
To much tempo running is not only not required in most (unless you are a pure runner, even then it's debatable) and it is almost always the intensity which leads to injury.