This seems a lot like trying to invent a problem to justify your metrics rather than acknowledging that your metrics don't align with the actual performance of the team.

There's no indication in the article that the team was struggling or under-performing, and there's no reason to promote someone out of a position they're thriving in just because the way they deliver value doesn't neatly align with how you're measuring value, especially if you can plainly see the value.

Here's what I've seen in the past: exactly the scenario you described, the "Tim" is promoted to team lead or architect or something similar, and now their calendar is booked up and they no longer have time to do the thing that brings value (and that they enjoy). No one on the team is happy, everyone is stressed, and in a year or so you'll start bleeding members. Tim either hangs around and is a mediocre whatever position he is, or he leaves to be a whatever position somewhere else where he can start with a new context and without loaded expectations.