An LBA (logical block addresses) is a mapping table implemented in the FTL to match between logical and physical pages/blocks in SSDs, my guess is that most SSDs (at least when they are empty) keeps the physical addresses in the same order as the logical ones (the physical address 0 is mapped with the logical address 0, 1 with 1 and so on).
When a page is changed the SSD controller copy the updated page to the cache, changes the page, mark the old one as 'none valid / stale' and then write the new one in a different location and update the LBA.
So, after a couple of writes even if the physical addresses were aligned with the logical ones, this order will be messed up!
Why does sequential writes have better performance than random writes then?
The lack of performance between sequential and random writes was regardless of the block size or the queue depth.