I once supervised eastern block students picking strawberries in England. At the start of the season I was given the worst 35 workers and another bloke was given the best 35 workers. At the start the other blokes gang picked 1 tonne more per day than mine. Throughout the season I treated my workers with absolute respect, we laughed, we drank together after work and we had a fun time with respect for each others jobs. The other bloke was an absolute arsehole to his workers, had no respect for them, all he was after was for them to pick as much fruit as possible.
At the end of the season, my team was picking 1 tonne more per day.
It's amazing what you can achieve from a happy work force. I guess these guys that are good with numbers wouldn't think about that.
By the way, the arsehole in the other gang had just finished a degree in agriculture! He knew it all of course, it's a shame he wasn't taught how to treat his staff.