I have a 2015 anthem 27.5 in a size medium. I had a custom bag done up by BBD in the eastern states (of Australia)...see the pic below. Worked well, just need to be aware of the usual frame rub issues and use some clear 3M if your frame is new. BBD also stock Oveja Negra bags, and their garage TT bag is amazing!

https://www.flickr.com/gp/134922683@N04/wg834N