You should ask him to a private meeting, praise the dickens out of his work, and then explain how making snide remarks publicly makes people focus on the relations in the team rather than the great work he's doing.

###Thanks!

You say, "he is also very good at work I have always put the team/business interests first and put him on paths that gave him many opportunities to grow and shine, defended him from other managers sometimes and helped him overcome stumbling blocks."

Lead with that.

Hey, I wanted to let you know that I've been really impressed by your work quality recently. You've been improving quickly and made a lot of big wins for our group and I really appreciate all the work you've been putting in to help us all out.

Everyone loves a compliment. Especially when you're being honest. It really makes you feel like a million dollars and makes you far more agreeable to whatever ends up said next.

###Output, not politics

You guys are being judged on your output as a team, and when the team doesn't look good, all of you get a little tarnish on your reputation. This person may not realize it, so it can't hurt to point it out:

Instead of focusing on how awesome our team's output is, I've been hearing a lot of hushed comments from other managers about our team dynamics. Apparently some of the comments like "Who ordered us to follow procedure A? Ha, and now we are doing B and it completely shows how A was complete nonsense!" are making them think that our great work is masking other problems that need to be addressed, and focusing on those problems instead.

I know you're just taking the piss, and that's fine internally, but when addressing people outside the team, toning it down will make us all look better, and will really let people focus on your output instead of politics.

Adjust 'taking the piss' for something appropriate to you, and if you don't want him doing this within your team, then obviously take that bit out. The point you want to make is that the snide comments are hurting how people perceive his awesome work, and giving him a way to prevent that from happening. Be honest, don't make stuff up if it isn't true, so adjust the above to fit your situation as appropriate.

You should ask him to a private meeting, praise the dickens out of his work, and then explain how making snide remarks publicly makes people focus on the relations in the team rather than the great work he's doing.

Thanks!

You say, "he is also very good at work I have always put the team/business interests first and put him on paths that gave him many opportunities to grow and shine, defended him from other managers sometimes and helped him overcome stumbling blocks."

Lead with that.

Hey, I wanted to let you know that I've been really impressed by your work quality recently. You've been improving quickly and made a lot of big wins for our group and I really appreciate all the work you've been putting in to help us all out.

Everyone loves a compliment. Especially when you're being honest. It really makes you feel like a million dollars and makes you far more agreeable to whatever ends up said next.

Output, not politics

You guys are being judged on your output as a team, and when the team doesn't look good, all of you get a little tarnish on your reputation. This person may not realize it, so it can't hurt to point it out:

Instead of focusing on how awesome our team's output is, I've been hearing a lot of hushed comments from other managers about our team dynamics. Apparently some of the comments like "Who ordered us to follow procedure A? Ha, and now we are doing B and it completely shows how A was complete nonsense!" are making them think that our great work is masking other problems that need to be addressed, and focusing on those problems instead.

I know you're just taking the piss, and that's fine internally, but when addressing people outside the team, toning it down will make us all look better, and will really let people focus on your output instead of politics.

Adjust 'taking the piss' for something appropriate to you, and if you don't want him doing this within your team, then obviously take that bit out. The point you want to make is that the snide comments are hurting how people perceive his awesome work, and giving him a way to prevent that from happening. Be honest, don't make stuff up if it isn't true, so adjust the above to fit your situation as appropriate.