Tell you a little secret. They don't want to lease. I was contracted to them back in 03-04 it's better to be an approved carrier, they are always calling you.
I think they find it is cheaper to simply broker out freight than it its to cover it with your own fleet. Esp. if your customer base is shrinking.
Some companies are always hiring because they want to find good drivers. You can't always tell from a phone conversation whether an owner operator is going to be worth your time or not. I've often hired people and sent them on shorter runs for awhile only to find out they aren't the kind of person I want working with my company. I've also found guys that turned into excellent drivers that I would have assumed to be bad based on phone conversations. Maybe that says more about how well I judge people than the effectiveness of recruiting practices. ha.
Also, if a company doesn't require a driver to only contract through them then there is no drawback for either the driver or carrier to hire on a regular basis.