Barrier 1-3 could be seen as squeeze barriers.
If they are slow to get going , they are often squeezed out of contention as to getting a better position to do their thing, especially if they are traditionally back markers.

As an exercise
Look at barrier 3 on its own .
LS 6th-9th
Include any Resumers X
Lay them not to run a place.
$5.00 & less in its Place price.
Bet level stakes .6% of bank.
8+ runners.

You will find, very few will even run a place.

Some days there will be heaps of barrier 3's being scratched, as if its a hoodoo barrier to some trainers & maybe they rather scratch the beast & do their entrance fee, rather than take on the dreaded Barrier 3 - weird.

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Cheers.