From the piece:
If I were Obama, I'd be of two minds about flagging these statistics. On the one hand, they certainly make his case for the middle class more compelling. On the other hand … this happened on his watch! Since 1948, economic growth has most benefited those at the bottom of the income distribution whenever a Democrat was in the White House, and it's most benefited those at the top of the income distribution whenever a Republican was in the White House.
Obama's first term, it seems increasingly clear, constitutes a dramatic break from this historic pattern. The U.S. economy’s current ability to expand—no matter who is president—without benefiting the 99 percent is something new. Perhaps we should do something to change that.