Well let me say after doing seasonal work for them this past holiday season... I know I hated the job. Only stuck with it for the extra money. After the season was over, NO WAY I'm going back ever again.. Its a extremely physical job, overwhelming for me as is the reason why so many don't last. I know a few of the ones that were in my group when I started dropped out after the first couple weeks.
They work you to death. Was an unloader, seemed like I was never fast enough for them (they wanted a full 18wheeler truck empty in 30mins doing it all by myself) So yea.. They said they are always hiring at the hub near me just because of the high turnover rate there.
All I can say is good luck to anyone trying to apply for this job. Be ready for very physical work. I've had my experience there and looking back, it really wasn't worth it.