I don't think this was a statistical analysis, but rather just the average change at Hired.com. The article does treat it as though it is an inference about the entire population, though, without justification, and their link goes to Hired.com, not an analysis.

Depends on how much salary appreciates elsewhere. It's quite significant compared to ny and texas (1.1% up + 0.3% down).

Salary is comparative by nature. If your worth increases less than someone similar, then it decreased.