Because clearly shaking it up in 2013 wasn't enough.
Legere, who has led the emerging fourth-place cellular company since September 2012, has overseen some of the biggest changes to the company — and as a result the U.S. wireless industry — in years.
In 2013 alone, he introduced a streamlined plan structure for new customers dubbed "Uncarrier," which all but killed off contracts and phone subsidies. Under his direction, T-Mobile then introduced the "Simple Choice" plan that brought into force unlimited international data roaming plans — something the wireless industry had been dining out on for years as a prime money-maker on business and international customers.
And, not content with that, the cellular giant brought out "Jump" which allowed customers to upgrade their phones twice a year — sending a clear message to Verizon and AT&T, whose policies require a two-year wait before their customers can upgrade, that such arbitrary rules were not an option. In just a few months, T-Mobile saw more than 2.2 million sign up for the service.
All at the same time T-Mobile transformed internally after its MetroPCS merger in the first half of the year. And Legere didn't even break a sweat.
Exactly what's on deck for T-Mobile in 2014 remains much of a mystery. That said, the picture Legere tweeted out suggests news coming out of the annual Consumer Electronics Show (CES) later this month, which could detail what's next in the fourth-version of its Uncarrier plans.
Also rumors spinning from last year could signal T-Mobile's next big thing: paying the early termination fees of customers wanting switching from the cellular firm's rivals. Another possible ding to AT&T, which Legere said he could "give a break... or not."
Such a move could be considered a near-death blow for T-Mobile's rivals, which would see the firm essentially pay defectors to ditch their current carrier and head to T-Mobile.
Also on deck, Legere said 4G LTE will "go faster, go LOUD," suggesting a deeper roll-out across the U.S. The next-generation speeds began a rapid expansion early last year in seven major cities, and pushed further into more than a dozen in the following months.
There was no mention or hint of T-Mobile making a punt for Sprint though. Late last year, T-Mobile's chief financial officer Braxton Carter floated the merger boat, suggesting it was "not if, but when."
"Let the transformation begin," Legere tweeted. And so it shall be.