I was really starting to agree with preach but the more I thought about it the more I realized it really won’t be that big of a deal. I remember Demonology was sim poorly at the start of the expansion. People on the forums said they couldn’t play this spec because how bad it was. I did it anyway. People in my guild assumed I was affliction. They saw my numbers as good damage, great in a lot of cases, and didn’t look any deeper. It was well after the first raid when the main tank noticed and swore up and down I couldn’t have been demonology that whole time. But I was.
Long story short play what you like. The more you play it the better you’ll get at it and pull some great numbers. Covenants will be the same way. You may not be world first best but you will do your part of the raid just fine.