You have probably fallen in to the trap of believing that every developer is the same, and that all of them can thrive in every team. That is absolutely not the case. A superstar on a team where they're doing work they want to do, that they find interesting, and that suits their skillset won't be a superstar somewhere else where some part of that equation isn't working.

Talk to them and figure out what's different between your team and their previous team. You might be able to change things to get more from them. If not, let them move on to another team where they can be better.

Not a superstar but this fits me pretty well. I was hired by a pretty well-known cool company after having apparently "aced" their interview. It was just that their interview suited me well, it was both designing big stuff and solving small problems which is what I had done previously at several companies when I always was in a team of two or three developers with technical ownership of a complete product.

Pretty soon after I started, it dawned on me that I would probably not partake in designing "the big" stuff. Partly because most of the big stuff was already done and whatever remained would probably be solved by some of the more senior devs. Any semi-large stuff would need to be fought over by the rest of the devs. What was left was drudge-work compared to all I had done before. Also most of my tech-skills (besides the programming language in question) were not needed and when I helped a colleague in another team working on something I knew pretty well, my manager reprimanded me after, telling me that our team couldn't spare the 2hrs I spent.

I was pretty unhappy and during this time was pretty far from living up to my own expectations. My manager never told me I was falling behind however so I don't know about their expectations. I quit soon after.

In my case I was moving from the experience of small companies and being "forced" to do everything, to a large company and only allowed to do very few things.

One suggestion: Give it time. Many (myself included) are “slow boils”. Probably every manager I’ve ever had was kicking themselves for hiring me 6 months in, but past the 12 month mark and things have turned a corner. Anecdotal for sure, but every previous manager I’ve had continues to randomly ping me about job openings.

I disagree with the other person who said, “Give it time…”

Read the book Difficult Conversations.

From the book, you need to prep by looking at the situation from your perspective and the other person’s. This has been very helpful for me in figuring out these tough situations. Then you look for the difference in those stories, hear the other person’s story from their perspective and work towards a solution.

Generally the more you put off these conversations the more you’ll regret it. And honestly it’s a weight off your shoulders when you do have them and you’ll often wish you had them sooner.

And most people in my experience hate starting these kinds of conversations so more often than not, in some way, they appreciate that you as their boss are starting it for them.

I'm also new to manager role, but I think the first thing is you need to talk with him. Try to understanding what's going on about him, maybe it's just he had some bad time for whatever reason now. You can talk with him based on the fact of his performance and tell him your expectations. Just try to find out what's going on first before making any judgement.

I recall one time when I had a manager tell me that I was not performing up to expectations. I had no idea. I thought I was doing pretty well. At the time I was pretty young and inexperienced, so not a huge surprise. He was calm but direct, did not turn it into a personal attack, and had some specific examples of things that needed to improve. I apprecated this, I worked on the things that he wanted me to improve upon, and ended up getting top perormance reviews not long afterwards.

superstars survive on and value their reputation above all else, you can use that to motivate. Review with the team how productivity is measured and the goals the team is striving for. Then, call out someone on the team by name who is doing the most to get the team where it needs to be and give them a reward. It doesn't matter what the reward is, a random sticker will work just fine. Your superstar will see the writing on the wall and step it up so they get the callout and reward next time.

I've seen this at work with a Managing Director and her direct reports. Direct reports to a Managing Director are hyper competitive and cutthroat. Think of them like the velociraptors in Jurassic World, if you can keep them focused and not killing each other or everyone around them they're a very powerful force. This MD would just hand out verbal "gold stars" on an all hands call. The DRs would get noticeably upset when they did not get the "gold star".

Don't approach it as a performance review as there are a lot of people who take some time to get up to speed. If the quality of work is good, then it can be a casual discussion over a coffee on challenges they might be facing and the sort of productivity targets you would like them to meet within X period of time.

In that context you could ask again if there are any issues they have or if there are any challenges they face that might make this difficult etc.

This way you can get your message through without it becoming confrontational or the other person getting overly defensive.

What are the full set of responsibilities of the team member? Are they being tied to previous projects? Is there something that is getting in their way? Is there a culture clash?

Also, understand that the new person is learning the context and team culture, and will take some time to get up to speed. How long have they been on the team? How long have you been on the team? The other team members?

There is a lot of context to consider. We can make a lot of assumptions based on our own experiences, but may end up sending you astray.