The *average* investment manager doesn't beat the market. If you're going to use unit trusts as an investment vehicle, the trick is to find those that *do* beat the market over time. They are out there. Allan Gray is one.
The one thing you have remember about investment managers is they are selling a product to you. Figures and graphs can be represented in a number of different ways and I guarantee you they have a team of people that sits there figuring out the best way to represent performance. Everything will be framed to give the best possible picture, even though strictly speaking it will be valid numbers being used.
P.S. investment managers as a whole cannot consistently outperform the market, because if they did they would effectively be outperforming themselves. I thought it was 20% of managers that outperformed but my research is maybe a bit dated, that 15% of managers is constently changing its composition however.