If you look at the recent studies behind motivation, the results of this study shouldn’t be surprising. As long as teachers (or other professionals) are being paid enough, the old factory model of bonuses doesn’t seem to be working as well in todays world.
This is true in business, where you see people laid off or given bonuses based on how well they did in a particular quarter, resulting in the long- term vision of the company being hindered.
Caring and believing in what you do and the people you do it with (be it colleagues or students) lead to growth. And that growth should not solely be measured by test scores. They are a quick way to collect data, but should be used with other measuring tools.