User blog comment:MegaWho99/Zoom Lighting Colour/@comment-32509213-20160916181049

The way I understood it, Zoom travelled back in time and convinced a younger version of himself (pre-Velocity 6) to embark on his plan. His yellow-lightning younger self would act as Jay Garrick/The Flash and provide hope for E2 and "help" Barry get faster, thereby having more Speed Force. Then his older blue-lightning self would take away E2's hope and steal Barry's more potent Speed Force.