Smooch,
It depends on what you are invested in at ML. If you're in total stock market-50% and total bond market-50% at ML, then you would have had a 3.9% return if you had bought VG funds.
On the other hand, if you would have chosen 25% VG Total stock mkt, 25% total international, 50% total bond mkt, you'd be at 4.9% YTD. If you sliced and diced and added in some of the mid caps and small caps and value funds from VG's "Domestic Stock - More Aggressive" category, you'd have a little higher returns. Large caps (which is what the total stock market index is for the most part) have not performed as well as mid caps, small caps, value, or international funds in general. My guess is that you are not in total stock market at ML, but rather in active funds that pick lots of mid and small cap stocks, and at least some international. Are you 50% bonds at ML? The long-term bond funds had about twice the YTD returns of the short term bond funds.
It is hard to compare how you would have done at VG unless you break down what you own at ML into asset classes that you would buy at VG, and then compare the two returns - apples to apples. Currently, it seems like you are comparing apples to oranges.
Post your portfolio if you want (in percentage terms of what you own), I'm sure some here can take a look.