Another week, another New York Times op-ed urging Democrats not to move left. The culprit this time is Steven Rattner, self-described “Wall Street financier” and, for a brief time, the lead adviser to President Obama’s Auto Task Force, who in a column yesterday warns his fellow centrists of “the freight train coming at us from the left” and enjoins them to turn away “candidates from the fringe of our party.”

Rattner’s argument isn’t really important: it’s the same one that’s been made and debunked a hundred times by now, in a variety of outlets. No, to understand Rattner’s dire warnings, you really only have to know one thing about him.

The reason Rattner’s time with the Obama administration was so brief, and the likely reason he missed out on his coveted post as treasury secretary, is because at the time, Rattner’s former private equity firm, Quadrangle, was being investigated by the New York attorney general for a zany kickback scheme set up to obtain investments from the state’s largest pension fund.