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Not sure I understand -is this supposed to be a good thing?
I’ve been out of the loop. I’m just now catching up on this. It feels like we’re in sci fi territory now.
Try it. Don’t lock your elbows, on the gun punch up with the elbow on the same side as the rear leg. You will rotate the hips like Bolt did or fall on your face.
If you want test results track down John Prior, he used to do testing in Sydney at Narrabeen for the institute, I believe he went back to England.
Alternatively if you have the strength you can do the bullet start Charlie had Ben doing.
Science fiction, maybe.
sady
You should not lock your elbows anyway. I doubt more weight transferred to the hands will do any good. Your turn by all means! 
I’m wondering if the higher foot placement allows athletes to get a better stretch reflex out of the achilles. when the new, higher tailed,blocks came out many coaches and athletes complained that it did not allow the competitors to get this, thus reducing block power. This could be an attempt to mitigate the effect of the higher back of the block.
For examples of complaints see the comments made by Ato in his blog Re JD, and Telez’s interview on the Canadian coaching site.
Of course, this can be a good reason behind it! I take it from that your toes don’t have to touch the track. So, I am wondering why a couple of officials I’ve seen correct sprinters on the blocks -was that the reason? I don’t know… But then again you have John Smith suggesting the heel touch the pad on the HSI series, otherwise ‘it’s like walking on your toes all the time’.
Related, but not exactly. JS seemed to be predominantly concerned with the fact that you cannot be stable in the blocks for that reason. Telez and Ato actually suggested that there is also a mechanical effect. However the final outcome is the same. In the case of the new blocks it may be possible to get the stability, but not the stretch reflex if there is one.
I’ve always hated those straight faced long pads that limit the stretch reflex in the achilles. This would be one way to get around that problem as well as slightly changing the angle to get you out lower without the need to load up your hands. I was originally bound by the old rule that your feet had to touch the ground till close to the end of my coaching days but it makes sense to use this if you are strong enough. If you are a beginner or not a strong starter even at a high level- like Allyson Felix, it might be better to stick with a traditional start.
Why should you not lock your elbows 
In some cases, locking the elbow makes it more difficult to pick the hand up off the track for your first movement (i.e. the hand flick up off the track should initiate movement at the start). For someone who is less strong (i.e. able to hold position), locking the elbow may steady the athlete. Again, it is an individual thing.
I agree with this analysis.
So, if most athletes at almost any level prefer the stretch reflex via shorter pads, why the introduction of those long ones? What’s the reason behind this? If they wanted to standardise things, they should have made everyone have contact with the track, no?
I don’t know really but it might have to do with R/T devices as well as start preferences but maybe it just allows more options for foot placements now that ground contact isn’t required.
When you lock a joint both stabilising muscles are in the relaxed mode, the NS is turned off when unlocked the stabilising muscles are semi flexed, the NS is on.
The story I heard was some coaches like to have the heels hard against the blocks so the quads do the bulk of the work in the first movement. After they removed the rule that the feet must be in contact with both the track and starting blocks a longer foot pad had to be introduced to allow both.
I believe it has to do with faster block clearance due to the absence of a backward movement of the heel. Clearly the ramifications of this weren’t thought through beyond the immediate effect.
From 1968 to 1999, the WR went from 9.95 to 9.79, .16 of a second.
From 2008-2009, Bolt took the WR from 9.74 to 9.58, .16 of a second.
How crazy is that?
Very crazy
Remember the discussion of ‘‘9.48 in 500 years ?’’ from 2003. Looking at less than 5 years now !
Block clearance time is a reaction.
The higher the feet in relation to the chest the shorter the stride. The lower the feet the longer the stride.
As Charlie said (I think) big toe along the track, ball of foot on the base of the block. The foot is at the closest angle we can get it the first landing angle. etc.