Interesting part is that the buyers were able to finance the deal. It must be VERY advantageous to the buyers. Which means Sprint didn't get a good deal.
And on top of that the buyer is free to lease tower space to other cell companies in the area too, so they can make even more off the deal by throwing some AT&T or T-Mo antennas up.
...this is not uncommon in the industry. it helps in several ways, the least of which is increasing cash flows for Sprint. not to mention, it gets those assets off of their balance sheet. by not having to depreciate those towers, their EBITDA benefits, too.
its a strategy to improve their financial outlook.