I would probably add a bit more color variation in the diffuse, as its reading as almost a flat gold color right now. Also turn down the spec quite a bit, as burlap is usually very dull and doesn't reflect much light. I'm a little confused as to why you couldn't bake a normal map from a high res model. Is this one solid…
i think you got too much high frequency stuff happening in the diffuse, and your spec and gloss seem non existent. if you want some really high frequency surface detail make a separate small tiling normal map, and overlay while removing the blue channel in the game engine. what are you using to preview these materials. for…