Is that 17% of 60% so 10% of total portfolio? Or 17% of total portfolio?
Either way, I think VSMGX is a perfectly good benchmark for you.
At the end of today, below are the YTD total returns from Morningstar.com
VSMGX - LifeStrategy Moderate Growth - 60/40 asset allocation using total market weights, unchanging over time.
VTWNX - Target Retirement 2020, 60/40 now, but changing over time
DGSIX DFA Global 60/40 - small-cap and value-tllted with DFA fund managers
VBIAX - Vanguard Balanced 60/40 but no international.
One thing to note is that the dispersion of returns from similar passively-managed mostly index 60/40 portfolios is about 0.25%. So I do not think that being 0.3% different from your benchmark is that significant.
Clearly, international has done worse the domestic this year, so VBIAX is doing better than the funds with international equities.
I also think the only way to do much better or much worse than these benchmarks is to have a different asset allocation. For instance, someone who panicked and sold out on Feb 11th for just a couple of weeks, then bought back in would way underperform. In contrast, someone who switched from 60/40 to 75/25 on Feb 11th would have outperformed even if they sold to get back to 60/40 yesterday.
And a change of stocks from 60% to 75% temporarily comes with risk and maybe not as much reward as one might think. If stocks go up 10% while at the higher allocation, that improves performance by only 1.5% total. If stocks up up only 5%, that extra 15% to stock improves performance by only 0.75% total. Of course, if one shifts to 75% equities and stocks go down, then that hurts instead of helps.