I think one article is looking at combined income of a family and the other is looking at single income. The author is rather dismissive of the justifying NYT piece as well which in my opinion raises a good point about our perception of middle class. Some people want to apply a rigid definition to the term that is defined by income which really doesn't make a whole lot of sense given the variance in incomes regionally. Others perceive it as more of a lifestyle whose membership is more determined by spending habits, additional expenses, other lifestyle decisions, etc.
It's like someone flipped a switch in the 1980s. It shouldn't be this way.