Obi-wan only wins when he has low ground.

Maul had high ground-Sliced
Grievous was more elevated-Shot and set on fire
Anakin was doing a back flip and was thus higher-Now he hates both lava and sand

Mmmmm, so it was a trick to tempt Anakin to take the high ground

Indeed

Obi wan is actually the king of the low ground, the I have the high ground scene was never scripted, it was actually just obi wan taunting anikin about his height, and George Lucas was filming

hhmmmm interesting

XD

Obi Wan IS the high-ground

and will always be