[Brightcolours]

It's difficult to compare a single sample of each lens.
The IQ difference at both ends could be related to copy-to-copy variation and nothing else.
If someone were to compare the average of 20 Pentax samples vs 20 Tamron samples, then we could draw some proper conclusions (as what lensrentals.com does).
One sample is just not enough to be sure of anything, beside copy variation.

I mostly disagree with that. Lenses can vary in AF accuracy, but that did not get tested. Lenses can vary in centring success, but these lenses are not decentered. For the rest, lenses do not vary very much, that is why reviews do make sense, also from OL and Lenstip (who do not average 20 copies).