Well sounds just like the crappy Mcelroy I work for.... They hire these poor guys straight out of school and promise them the world and get a bunch together and only keep the cream of the crop....
Hard to believe you failed because of shifting. How many tries did you get? Oh, and what's a gear master?
Maybe you and McElroy where not a good fit. Good news is there are plenty of others. That said, I've always heard good things about McElroy.
If I owned a trucking company, that sounds like something I'd be doing. Getting students straight from school allows you to train them for the way that works best for the company. They haven't had time to develop bad habits at other companies, and they don't have expectations based on past experience. Those that don't work out would be weeded out.