Last week in the WSJ, Joe Light shined some light on a study that took issue with Morningstar's ability to forecast winning mutual funds.
The paper looks at Morningstar's overweighting of "corporate culture" as the major input into what the research firm calls, "corporate stewardship".

Corporate culture is one of the mushier components, answering questions like “do talented investors spend their careers at this fund firm?” To see what value the culture rating adds, Pace University professors Aron Gottesman and Matthew Morey took Morningstar’s corporate culture ratings and compared them to fund performance between 2005 and 2010, finding that the two don’t necessarily go hand-in-hand. (Can Corporate Culture Predict Mutual Fund Performance)
Morningstar responds
Well, the mutual fund rating firm wasn't going to let this slide without a fight. The WSJ published Morningstar's retort:There are some serious flaws in the Gottesman-Morey study. First, we’re skeptical of any study that finds that fund expenses have no predictive value. Expenses have been shown time and again to be predictive of performance. We think it’s also important to point out that Gottesman and Morey did find that a high Culture Score was strongly associated with low fees, long manager tenure, low turnover, and fund survival. These are all very positive qualities in a mutual fund... (Morningstar challenges study that questions its ratings)