Diamond Ore Generation Has Been Nerfed

PLEASE DISREGARD THIS BUG - IT WAS SEED SPECIFIC. MODS/ADMINS, PLEASE DELETE

As of the snapshot update last week which introduced a -64 Y Axis world generation the Diamond ore generation has changed.

Previously if I mined 6 (or 7) blocks from the centre of clay patches in rivers in plains biomes (offset on the Z axis) I always found diamonds between Y axis 5 and 11. This method of diamond mining was about 95% accurate.
However, since the update it's only about 30% accurate and the offset has changed from Z axis offset to X axis, and the offset amount appears to be random, or between 2 and 8 blocks from centre of clay patch.

Unless this is seed specific.
I tested this in a new world I created after the snapshot release so it is a different seed to the one I normally use for my survival world.