Excellent fight and huge win here for Ishida. He controlled Melendez with superior wrestling and a better, more aggressive gameplan which caused the Cesar Gracie product to counterfight much of the time. This fight also helps shake up the rankings, especially in combination with Kawajiri's win. I'd also say this gives Gomi a bit of an image boost. After a loss to Diaz, it's a helpful reminder that Gomi absolutely destroyed Ishida. The fact is at this level, the difference between the abilities and talents of fighters is miniscule, so "upsets" like this are going to be common.
Part 2 and Part 3 of the fight here.