Few things happened:
1. MHDD scan detected two <500ms blocks

Called seller, told my new hdd has dozens of slow 50-500ms blocks and they agreed to replaceme.
2. before replacement, I've zeroed first with wd data lifeguard, then zeroed again in hddscan, hddscan results showed a lot more of green blocks and orange (2-3x more)
3. after replacement, I've launched mhdd straight away, results are very similiar to mhdd scan of previous hdd:

SMART gives no interesting info (no errors with cable, no reallocated sectors etc)
I don't know what to think. Few options:
a). replacement hdd is from the same batch as previous (substandard batch?)
b). just super unlucky
c). my motherboard controller is wonky (asrock p67 extreme4, bought in 2011, tried with different sata2 port and cables are short in length and new, also for this mhdd scan, I've plugged off all other hdd/ssd, so only this replacement hdd was detected in mhdd)
d). thats just how wd red 4tb are now
Any thoughts?