MFI vs. Wilshire 5000

I'm having trouble deciding whether MFI is really winning - I suspect it is, but I'm trying to figure out by how much. My MFI portfolio is up 13.43% total, compared to the Wilshire 5000 that's up 14.78% over the same period - since I started my portfolio. But my portfolio is affected by having three separate buy periods. So is it by averaging the returns since the three buy periods? In this case, it's 16.2%, compared with the average change in Wilshire 5000 of 10.67%. The IRR of my MFI portfolio is 37.0%. I think that's probably the key; and in this case, it would be compared to the IRR of the Wilshire, which is 25.1%. So, yes, MFI is winning.

The real problem is my latter two sets of stock picks - they've stunk. The first set returned 38.58%, compared to 15% of the Wilshire; the second returned 8.92%, compared to 13.4% of the Wilshire, and finally, 1.1% from MFI compared to 3.6% of the Wilshire. What did I do right in the first set of picks that I didn't do in the second and third picks? Or more likely, what did I do wrong in my later picks that I didn't do in my first picks?