Before the regular football season starts, in high school anyway, the team will go through extensive practicing and a lot of hard work. You might even call it a refiner's fire. Perhaps, one of the most significant reasons the coach will put his players through this is to weed out the ones who are too weak, or who simply do not want to work hard.
The Lord is our coach, so to speak. He wants us to enjoy the blessing of playing in the homecoming game and enjoy a successful season in the promised land. But He must test and try us before we can come up out of the wildnerness. If we will prove to Him that we will keep His commandments then we will reap the reward.