Competition really hasn't been healthy, beginning with the Kepler generation. Ever since then, AMD has been unable to get a solid win, and most of their cards have been rebrands. They're still running some first-gen GCN chips (dating back to 2012) in their current lineup. Heck, some of their prices have actually increased in the last few years (eg the 390 rebrand raised the price by $100).

NVIDIA held the upper hand with GK110 (780/Titan), then AMD dropped the 290X. This forced NVIDIA to readjust their prices and release the 780 Ti as an interim measure, but they held onto their lead position. Then NVIDIA started with the Maxwell series, which drastically improved both performance and efficiency. AMD tried to respond to the Titan X with the Fury X, but NVIDIA cut the legs out from under them by releasing the 980 Ti. Now once again AMD is behind the performance curve - NVIDIA has staked out the high-end space with the 1080 and the midrange with the 1070, and AMD is stuck in the low-end market with the RX480 until NVIDIA can get GP106 out.

AMD's response to the 1080 is going to be the Vega 10 chip, and unfortunately it's unlikely to be released before Q4 2016 at the earliest (more likely Q1 or Q2 2017). NVIDIA already has GP102 coming down the pipe, which is going to be a Titan/1080 Ti, and they'll drop that when they feel it's necessary to spoil AMD's sales.

That's the story of AMD and NVIDIA recently. AMD has put out some cards that were good value for the money - both the 7950/7970 and 290/290X have been very long-lived performers (and will likely continue to perform well thanks to DX12). But they haven't taken the top since 2012, all they can do at this point is force some price reductions. Like it or not they aren't a serious competitor in the GPU space any more than they are in the CPU space. They are a budget choice, not a serious contender.