IRS Pre-trade Transparency

Saw an update from ISDA recently. They have released the results of a blind test to assess the transparency & competitiveness of the plain vanilla USD & Euro swap market. In short, it’s a competitive & transparent market, with maximum spread between best & worst swap rates at 1.3 basis points.

Makes me wonder what evidence was used to justify the SEF requirements in Dodd-Frank. When I google for “evidence for swap execution facility” I cannot see any clear economic evidence for a SEF that would lead me to reject the analysis by ISDA.

Can anyone help?