First of all, industrial metals are the most significant sub group in commodities we watch for signs of economic strength. For more on this check out John Murphy's intermarket analysis books.
Yeah the CRB is up 10% YTD, but notice how little industrial metals have participated. It's clear, especially of late, the true economic strength isn't there. This is complete breakdown city. Clearly, industrial metals aren't driving the move.
Furthermore, notice how dr. copper has traded since bonds started rallying at the new year. The action is highly inversely correlated, just as one would expect. Again, signaling a weak worldwide economic backdrop.
As far as CRB is concerned, it can keep rallying for who knows how long, this is has been an insane winter. Hell, it's a record low negative 20 degrees in mid-Michigan as I write this. BTW, It's March tomorrow!
At the end of the day though, the markets have already tipped there hand. The global economic backdrop isn't positive.