We hire this new guy, a senior-level guy (all we needed was a mid- to junior-level guy to do some work) and he's rewriting fundamental architecture in the code and database. The other developer (junior-level) just fell in line and did it the way he wanted, but it's interrupted my work and now it's broken in staging. I'm having a hard time convincing our managers that this isn't a good way to go about things and the new guy insists that we have to do it this way or it's "wrong" or "poor" and he's even admitted he won't work with a big chunk of our architecture and is just writing his own way of doing it.
Has anyone else encountered this and what was done about it? What is standard practice?
I've had to do this before. Sometimes as a senior guy, you just know a project isn't going well and it's time to make changes. But there's usually an organizational channel of reviews and approvals to go through, you don't just "declare" that you're rewriting stuff unless approval is reached among those in the approving space, and appropriate communication happens to everyone else. Sounds like some or all of that part isn't happening at your company.
It sounds like your new developer, however good he may be, lacks people skills. If he believes your existing codebase could be better, then he should present to the rest of you his proposed changes and how those changes could be beneficial. But for him to rewrite your architecture without permission or even discussion is very poor practice. You could explain to your other managers that even though the changes may be good, the lack of communication and coordination is very bad.