T-Mobile COO Mike Sievert has some big *bleeping* shoes to fill

“Have you guys used AT&T’s network in New York?” asked John Legere in Las Vegas on January 9, 2013, of press and other audience members attending his first major press conference as CEO. “It’s crap!”

It was that last part that roused me out of my mid-CES stupor and forced me to pay attention more fully. Wait a minute, I thought, did he just seriously call AT&T’s network crap? He had, and would go on to do so many more times. Legere didn’t reserve his ire for AT&T. He lobbed similar insults at Verizon Wireless, and eventually came to refer to the nation’s two largest carriers at “dumb and dumber.”

Legere’s CES 2013 press conference was just a warm-up. He really let loose at the company’s first Uncarrier event in March of that year. In between the condemnations of T-Mobile’s competitors, Legere disconnected device payments from service plan costs. He also lowered some pricing and made it easier for consumers to see where their dollars were being spent.

Standing to Legere’s right during both these and subsequent Uncarrier events? You guessed it, T-Mobile COO Mike Sievert. Yes, Sievert has literally been Legere’s right-hand man through it all.

It’s with perhaps only a small measure of surprise to learn that Legere’s time at T-Mobile’s helm is drawing to a close. Legere arrived as CEO in September 2012 after a stint at various companies, including Global Crossing, Dell, and, believe it or not, two decades at AT&T. At the time, T-Mobile was the fourth-place network in the US, far behind the two market leaders as well as third-placed Sprint.

Through more than a dozen Uncarrier moves over the years, T-Mobile surpassed Sprint and also effected real change in the industry. AT&T and Verizon were often forced to follow T-Mobile’s lead as it sought to break down the traditional wireless business in ways that benefited consumers. Legere may have caught flak for is unorthodox style and brash attitude, but it also won him loyal fans.

In his usual fashion, Legere announced the news of his departure through his Twitter account.

“I’ve got some important news! On May 1, I’ll be handing the magenta CEO reigns over to @SievertMike as my successor,” he tweeted. “This move has been under development for a long time and I couldn’t be more confident in the future of @TMobile under his leadership. You’ve heard me joke that he’s ‘my son,’ but in reality, since I hired him in 2012, @SievertMike’s been my mentee, my secret weapon and my friend. In our time we’ve launched 16 #uncarrier moves, shifted an archaic industry for consumers and wreaked havoc on the competition.”

According to T-Mobile, this transition has been many years in the making. Legere will spend the next five or so months helping Sievert with the transition. He’ll then remain on the company board for at least some time after the May 1, 2020 change.

It may not be 100% clear what Sievert’s role was in all the changes at T-Mobile over the years, but surely it was a big one. At press events, after Legere was done announcing the large bullet points, Sievert would often take over and handle discussing all the finer details.

If you ask any T-Mobile employee how they feel about Legere, most will say they love him. He created a specific culture, imbued a certain swagger that helped T-Mobile grow over the years. Sievert says things will keep moving in the same direction.

“The Uncarrier culture, which all our employees live every day, will not change,” said Sievert in official remarks. “T-Mobile is not just about one individual. Going forward, my mission is to build on T-Mobile’s industry-leading reputation for empowering employees to deliver an outstanding customer experience.”

While I truly believe Sievert will give T-Mobile his best, there’s no question he’s stepping into a big, Legere-shaped and curse-filled void. What remains to be seen is if, and how, Sievert shapes not only T-Mobile, but the industry as he defines his own era as T-Mobile CEO.