When/why did Warsteed requirements change?

I went to go check my progress recently on earning my Warsteed and noticed that the requirements of doing so has changed. It is no longer simply earning 100 frontline victories with the same GC... now you need to do it in the Borderland Ruins exclusively.

http://i.imgur.com/3PkvaTj.png

I've read over patch notes but never saw this. But this really sucks. I'd love to play more Borderland Ruins but it doesn't happen no matter how long I queue. Didn't you learn your lesson from the Seal Rock achievements?

Counting over my wins and my achievements, the requirements actually didn't change, they just changed the wording. Your win count will go up even in Shatter/Seal Rock; mine have been.

Error in the description. Can still do any Frontline map and it will work towards it.

Source: only recently switched to flames and on 30ish wins exclusively on Shatter due to Garo.

Its always been like that.