Uneven is the opposite of uniform and predictable. If the road is uneven, it's bumpy and rough, and you’ll have to dodge the potholes.
If your performance as Hamlet is uneven, your "To be or not to be" might be brilliant, but you mumble through "Get thee to a nunnery!" If the economic recovery is uneven, it's not the same in every sector — maybe manufacturing and exports are picking up steam but the housing market is still lagging. If your soccer team of skinny 12-year-olds is up against a team of beefy 16-year-old giants, it's an uneven match and likely to be ugly.