By praising McCoy's effort he is encouraging him to keep working and to try harder.

"Children praised for the effort, on the other hand, performed roughly 25% better on the final set of problems compared to the first."

https://hbr.org/2011/11/the-trouble-with-bright-kids


"So, what does predict success? Research tells us it’s using the right strategies that leads to accomplishment and achievement. Sounds simple, but strategies like being committed, recognizing temptations, planning ahead, monitoring your progress, persisting when the going gets tough, making an effort, and perhaps most important believing you can improve, can make all the difference between success and failure."

http://blogs.wsj.com/atwork/2012/07/24/the-success-myth/