[mst]

Somehow you ignore that DPReview posts post processed images, and Lenstip does not? ;-)

That's not exactly a fair description of the different approaches DPR used the default sharpening parameters in ACR, while lenstip for ages claims that it's the best approach to not apply any sharpening during RAW-conversion at all... which is something no one would ever seriously consider in real life, and their sample images regularly show why

In any way: the different approaches definitely do not explain the very visible differences between the sample images. The DPR sample is obviously not focused on the objects in the image center, but maybe (manually?) focused to give good corners (the corners look better than the image center to me). The lens tip samples a focused in the image center obviously, with the corners not in the same distance and thus blurry.

The dpr sample image shows that the lens can deliver good corner sharpness when focused properly. The lenstip samples linked to in this thread actually tell nothing about the lens' potential in the corners.