Whenever you're making a transition from one type of company to another, the hiring manager is going to be very concerned about whether you understand the kind

Whenever you're making a transition from one type of company to another, the hiring manager is going to be very concerned about whether you understand the kind of transition you're making, and are able to bridge that gap. If you've been in an enterprise environment and are interviewing at a smaller company, they're going to be concerned that you're a hidebound cog who just sits there and waits for someone to tell them what to do (in triplicate), so they'll be looking for signs that you have initiative, that you don't think of things as "someone else's department," that you have the flexibility to roll with things that deviate from a strict process; if you've been at small companies and you're interviewing at larger ones, they're going to be concerned that you've just been ignoring all best practices and doing stuff with bubblegum and baling wire in a half-assed way. My suspicion is that in those interviews, you didn't really allay those fears. Maybe you seemed impatient with process, maybe you came off like a cowboy, maybe you said things like "yeah, I know you're not supposed to make live code changes on production servers, but sometimes that's just the most effective way to get things done, you know?" Or... maybe the company size thing is totally unrelated, and you just didn't wow them, who knows. But it's not at all impossible to go between different types of companies, you just need to be aware of what's going to be different between them, and how you can be an asset to that type of company.