Ended up on a less preferred team after a small re-org - How to navigate this?

First, I recommend going through these 2 resources:

• Effective Communication Guide [Part 1] - Core High-level Principles - Your situation is a communication exercise, and this video goes through some crucial things you should keep in mind here, namely empathy.
• "How to drive my promotion discussion with my new manager?" - This is a very different situation compared to yours, but the broader theme of having a crucial conversation with your manager still applies.

How To Get Onto The Team You Want

• Your initial goal shouldn't be "I need to convince the managers that I should be on this other team.", it should be, "I want to understand why I was put on this other team." Whenever you're put in a situation where you don't agree with the result, it's important to suppress the common initial instinct of just going in, being sad/angry, and disagreeing. In order to have productive dialog and a chance of getting the outcome you want, you need to be empathetic.
• Talk with the managers (both your old/new one) and other stakeholders on this decision on why they made it this way. Maybe this new team needed an E3. Or maybe they needed someone on a certain stack which you're familiar with. Whatever the reason, try to understand it as deeply as possible - Maybe there's some angle you weren't aware of that this could be good for you!
• After you really understand the situation, figure out if you still want to push back. If you are, I highly recommend coming in with a solution and not just asking for a change. A super common mistake I see with software engineers and just people in general is that they come charging in wanting to correct a perceived mistake, but they don't bring a plan to do it. In your situation, if you were to be moved to one of those better sub-teams, someone will likely need to swap with you. You should have an idea (or multiple ideas) on who that could be.
• On top of all this, it's important to understand incentives: Every manager wants their reports to be as impactful as possible. And this incentive aligns with you as you also want to be as impactful as possible as a Meta engineer. Explain why you would be a much better fit on the other team you want to be on.
  • Are there projects of this team that you're an expert in? Do they have unfinished work?
  • Do you have very strong relationships with certain members of the team that really amplify your productivity?
  • Is there some aspect of the team's working style and culture that really resonates with you?

How To Make The Most Being On A New Team

• First, make sure that everything from your old team carries over, especially your promotion plan to E4 if you have one. Here's a discussion that talks about how to do this more. Talk to your old manager and make sure that they sync with your new manager about your growth plan, your growth progress, and just who you are as an engineer in general.
• Since you're all in the same org, there's no reason that you can't maintain prior relationships. Put your old teammates on your diff reviews. Continue having 1 on 1s with your old manager, at least monthly or maybe even biweekly.
• The most important thing to remember if this scenario is what ends up happening is to see it as an opportunity rather than a setback. Mentality plays a huge part in your performance, and having a "glass half empty" outlook will hold you back. The opportunity in this scenario is that you're on a fresh new team but you have this existing asset of connections to sister teams. This allows you to come up with XFN impact by working on projects that brings teams together. Admittedly, this is more of a behavior I'll see from E4s growing to E5s, but there's no reason why you can't start doing this earlier!

Hey,

If you feel really passionate about the other team or think you have some unique knowledge to contribute there - best is to just talk to your manager and say whatever the reason is in a very mature way. It is both helpful for the company and manager if you are working on things that you are passionate about. No manager wants people on their team to be working while being unfulfilled.

Having said that, I recommend you to see it as an opportunity to work on something else, people who do really well are resilient and can quickly accept and adapt to the new situation. In big tech, such changes happens all the time, this would be a good opportunity to build the muscle of resilience.

Overall, I say approach the whole thing with a lot of emotional intelligence and maturity, it is fine to talk to your manager but if a change can't be made - accepting and adapting to the situation shows highly on you.