MTGE is a cheaper stock and should do the same. There is more value creation at the current stock price in aggressively buying back your own stock (and perhaps selling agency MBS to keep leverage constant) with lower risk. Then again agency MBS is pretty darn cheap as well, with current levered ROEs after hedging costs in the mid-high teens.
MTGE is extremely cheap and I think that has a lot to do with it's sister being AGNC. The liquidity is just not there in MTGE the way it is in AGNC. So what you have here is a largely mispriced MTGE compared to AGNC. $23ish would make this equally priced with AGNC. If you have guts, you can short AGNC and long MTGE to make money. I think the values will actually cross paths at some point. Might not be for some time.. but definitely believe MTGE will overtake AGNC at some point.