Blood has no 'soft caps' or 'minimum thresholds' with any Haste, or any other stat. Secondary stats for Blood are all close enough to each other in value that you should prioritize item level over secondary stat itemization for nearly any piece of gear, except trinkets and rings. Versatility and Haste are very close in value — while Versatility is numerically better than Haste, the two are close enough in value that many Blood Death Knights prefer to prioritize Haste, as increased Haste allows for better reactions, which helps maximize Death Strike efficiency.