Are you sure the '15 are different to the '14 ones?
Now, that is a good question indeed. The part numbers in the manual looks like the old numbers, but that's not really anything to go by. If we see here, it's listed as a new and updated part:
http://www.teamxray.com/xb4/
And visually, I think the ones in the '15 box looks just a wee bit more beefy compared to the '14 ones.