If elected, we'll get so many great words, we'll get bored of words!

The article literally has a chart showing that the current candidates are all speaking at a higher level, and that the remaining candidates, Democrat and Republican, are speaking at 8th 9th, and 10th grade levels. Of the current cohort of candidates only Kasich is near Trump.

If you're talking about presidents (which is unfair, the type of speech you give as president vs candidate, and debates are different), it's clear that although the trend was downward, for the past few presidents the average level was about 8th grade:

http://www.vocativ.com/interactive/usa/us-politics/president...

Trump speaks at a 4th grade level. Probably intentionally.