The theory behind the TIPS:IEF ratio chart is that TIPs (Treasury Inflation Protection Securities) are bonds investors buy to provide protection against inflation. The principal of a TIPS increases with inflation and decreases with deflation, as measured by the Consumer Price Index. Dividing the TIPS bond fund with a bond fund that tracks the "belly" of the yield curve gives us a viable way to track whether inflation or deflation is gaining momentum in the economy.
In all fairness a case could be made that "Operation Twist" was largely a sterilized program in that the FED was selling Two Year US Treasury Notes and buying Seven to Ten Year Treasury Notes in order to keep interest rates low on the long end of the yield curve. But I don't have the numbers to determine whether or not they bought more seven to ten year notes than sold two year notes. But as a "QE" program it was not of the magnitude of the previous two programs.
Nevertheless, it appears that the FED is "pushing on the proverbial string" in its efforts to buoy risk assets.