Midstream MLPs were, until 2014, a fairly proven business model. However, in the time since, they've clearly been out of favor with the market seeing their stock prices drop, increasing their yields. Ordinarily this is a good thing, however, the midstream MLP business model relies on some fundamental stability in the unit price.
Due to growing energy consumption and production in the United States, along with long-term energy needs, investing in the currently out of favor MLPs is a great way to build assets in strong companies and gain long-term income and income growth.