Sprint finally lost its number three position in the US market to T-Mobile, and is still battling to deliver on seven years of promises (since the launch of Xohm) to offer the highest performance network. However, after an apparent crisis of confidence earlier this year, majority owner Softbank is demonstrating its renewed faith in its problem child, buying two new tranches of shares this month and upping its stake to just over 80%. This happens against a changing market landscape which even Softbank could not have predicted – the rising importance of WiFi, and therefore of the cable companies, and the wave of new alliances and rivalries that is generating. Softbank paid $86.9m for 22.87m shares on August 13 and…