I think Son's intent was pretty clear, that HE wants to/is going to change wireless network here in the states and personally takes an interest in it.
As you can see he doesnt mention Marcelo as a driving force. This move to come out is more to protect his reputation as a businessman, especially since Softbank dumped billions into Sprint and the failed merger with T-mobile.
The shorts believed Softbank would grow tired of Sprint and sell their interest, but contrary, the turnaround is coming and the shorts are sensing it.
*Improving Network
*New CFO
*Stock buyback
*Continued Aggressive Pricing
*Son is speaking confidence about Sprint to Markets, He has stepped up where Marcelo should have.
IMO- Look for stock run to $5 in 2-3 weeks
IMO- CEO Marcelo will be replaced
IMO- Stock price will sprint to $10 afterwards