Didn't SE says something about having a real, actual, training mode at some point? If I'm not mistaken, they also responded to the player interest in a Pvp mentor system ...

I expect they're busy until season 2 starts, but it would be nice to have an official training method of some kind, especially for new players. Until they officially get around to it, things like this are probably healthier than jumping straight into ranked 4v4 matches. Anything to ease the blow on the fresh blood is probably better than nothing.