Guys this isn't really about the duel itself, well I mean it is but this is more about the blog post then the duel just the duel not the battle. The guy also addressed the duel.
Next point: Mace only fought as a perfect equal with Palpatine. The novel is very clear that Mace, even when his speed and combat efficiency are so acutely aggrandized, is still only an equal with Palpatine in a duel.
Vaapad made him an open channel, half of a superconducting loop completed by the shadow; they became a standing wave of battle that expanded into every cubic centimeter of the Chancellor's office. There was no scrap of carpet nor shred of chair that might not at any second disintegrate in flares of red or purple; lampstands became brief shields, sliced into segments that whirled through the air; couches became terrain to be climbed for advantage or overleapt in retreat. But there was still only the cycle of power, the endless loop, no wound taken on either side, not even the possibility of fatigue.
--Taken from Revenge of the Sith
Another source even bears mention that Palpatine forced Mace back.
In the inner recesses of his private office, the Jedi confronted the Chancellor. Palpatine produced a lightsaber hidden in his sleeve and let the dark side flow through him. It granted him unnatural dexterity and speed—enough to quickly kill three Jedi Masters and force the mighty Mace Windu back.
--Taken from The Complete Star Wars Encyclopedia
This proves that Mace is incontestably not a better duelist than Sidious regardless of what some may think.
Which leads us to the next point: If Mace isn't a more skilled duelist, how did he win? Setting aside the possibility that Palpatine allowed him to, the novel shows that Windu won by exploiting Palpatine's fear which caused him to become distracted and slow down. Mace felt fear emanating around the office, which he believed was Palpatine's, and abused it by breaking the window, resulting in Palpatine hesitating when he stood near it for fear of falling down. This allowed Mace to land a blow that disarmed him.
Someone really needs to write down a list of all the most asked star wars questions, sneak into Skywalker ranch and slip a note with all the questions on it under the door and some how get George Lucas to address them through starwars.com or something haha (just joking