Nothing that's happened to Windows Phone so far is the result of Satya's leadership.
I think you guys are exaggerating how much time it's been. Satya took over as CEO in February. Windows Phone 8.1 released just two months later in April - obviously he couldn't do anything in those two months.
Devices take at least 12-18 months from inception to release. Usually even longer than that. Any devices releasing this Fall were planned, designed, and mostly tested before or shortly after Satya became CEO.
Even the plan to release Windows 10 some time next year - on both Desktop and Phone - was decided under Ballmer.
Windows 10's actual release, and devices which may go along with it, will really be the first Windows thing that Satya has any real influence over.