Sometimes these things happen quite randomly. You'd think that a big company like IBM would have a long line of people ready to take on a juicy project like this, but at the time, all of those people were tied up with more pressing work (customer commits, a high-profile performance project, etc).
Also, I've clearly glossed over a bunch of details but I wasn't hired as a team lead. That being said when management saw that I was capable of driving the team (mostly) on my own, they progressively stepped back further and further until I was essentially running the team. This was over the course of a few years, which I've compressed in the writeup.
All that to say that career ladders aren't fixed, and if you find yourself in the right place at the right time, you can bypass a lot of the traditional ladder climbing.
Also, I've clearly glossed over a bunch of details but I wasn't hired as a team lead. That being said when management saw that I was capable of driving the team (mostly) on my own, they progressively stepped back further and further until I was essentially running the team. This was over the course of a few years, which I've compressed in the writeup.
All that to say that career ladders aren't fixed, and if you find yourself in the right place at the right time, you can bypass a lot of the traditional ladder climbing.