WiMax was a FAIL, but given the options they had at the time, they HAD to do it because they had no other choice! When they merged with Nextel (yet another bad choice) they got 2 different bands of spectrum; 800Mhz and 2500Mhz, of which both had strings attached. The 800Mhz had interference issues with public safety (this is the boiled-down way of saying it, I know the technical reasons too) and so they had to endure an 8yr re-banding process that saw them loose some of this spectrum and not be able to launch LTE or voice on the rest until last year. They were compensated with the 1900Mhz PCS G-block spectrum, which sprint launched LTE on, but it doesn't have the propagation characteristics of the lower band spectrum. The 2500Mhz spectrum has even worse propagation characteristics, but is great for urban capacity (where is it most needed anyway) but had build-out requirements that had to be met or the spectrum would go back to the government.... this is where they had to choose WiMax, because LTE was not going to be ready for deployment until after they would loose the spectrum! It was a bad situation that sprint's hands were tied.
To try and take some of the financial strain off sprint because they did not have the resources to complete a full WiMax buildout (smaller propagation = Many extra towers = huge costs) they did a joint venture with a company called Clearwire, where they gave them their 2500Mhz spectrum and money and owned 51% (49% voting), but other investors would also invest and Clearwire would sell service in addition to providing it to sprint. Well, deployment was slow and money dried up, other investors did not want to invest more, so sprint had to keep dumping money in just to keep the lights on.
Dan Hesse has turned things around, but not to the extent that is outwardly visible. He has overseen the shutdown of an aging network infrastructure (Nextel), the complete gut & renovate of all old towers (Network Vision), the purchase of Clearwire so they could properly integrate the towers and spectrum, and the controlling interest of Sprint being purchased by a telecom with much greater financial leverage that will secure their future (merger with T-Mobile or not). That being said, I think that much of his compensation this year had to do with the Softbank transaction, but it is still very high!