WTI futures are 1000 barrels per contract. The trading range for the day was 58.17 dollars per barrel. Assuming they sold their TAS at the top, it settled at the bottom, and they bought their normal contracts evenly over the whole range, they made 0.5 * 58.17 * 1000 dollars per contract. That's 29085 dollars per contract (!). If they made 700 million dollars, then they turned over 24067 contracts. So they sold 24k TAS, and then whittled that position down to being flat. 24k seems like a rather big position for a firm like this.
The story does mention that they changed clearing firm after this happened. So perhaps their clearer had been lax about setting their risk limits properly, and after this happened, realised it was a near miss and tried to tighten it up, at which point they jumped ship.