I wouldn't need to download the file. It is unacceptably soft across the frame (assuming that Google Drive is not heavily compressing the file). Most likely it is the lens. I would do at least one more test, taking f/8 distance photos at infinity, 3m, 2m, 1.5m. The sharpest most likely will come at 2m - that's where mine is at for infinity. The 14mm is so wide, live view focusing can be challenging for certain scenes. It would work well for a newspaper (and that's another good test), but not for most landscape situations. I don't have the K-1, but that big, bright viewfinder might be better for focusing in good light than focus peaking.
Not having shot the 14mm on FF, I have no idea how soft it would be in the corners (especially if you feel strongly about correcting the significant distortion on FF). On the K-3 and other crop lenses, it is amazingly sharp into the corners.
Nothing in the album linked below is remarkable, just chronicling a day outing - but it happens that they all were taken with the Samyang 14mm (designated 12mm in EXIF). Even the low light inside photos are pretty sharp across the frame:
Winter Carnival 2014 - James Robins - Powered by Phanfare