James, the co-captain, has called for a pre-game meeting before our next game. Since the game is much later, it will be easy to do so. Players getting there right at the start of gametime has always been an issue - for early games, most people are coming straight from work, and we live in an area where the traffic is awful. Just so you know, by doing it this way, you're pretty much ceding your authority to all. You're not making a decision--you're letting them do it, and you'll follow their lead. If this was a divisive matter, it'd be one thing, but from what I've gathered, it's not. It sounds like a situation where you need to make the call.
In answer to another question, no, there have not been any players that have left due to Luke. There has been one who had to take a break for personal/professional reasons, but it was entirely unrelated. He plans to return in a few months.
Anyway, the pre-game meeting will basically give everyone a chance to air out what needs to be said and do what needs to be done. If it turns out that the team would prefer to keep Luke there, I will step down as captain and let things fall where they may.
I only say this, as bluntly as I do, because I've been in your shoes. Almost exactly. It wasn't a sports team, but it was a team (several), and I took the drawn out, softer approach to dealing with some people who were tremendous bullies. People were polite to me about it, and privately supportive, but in the end, it killed the team/community.
I've put your plan into action three different times, in three different contexts, and each time has failed. Even people who said they'd stay, they all bailed at the first polite chance they had. It killed the team/community. They may do that same thing this time--no one's left yet, but when next season rolls around, some may decide to "skip this season" or "try another team."
For the sake of your team, wear your spine proudly, and your authority with steel and modesty. You're captain for a reason. It's all right to rise to it.
I hope you realize I say this not out of criticism, but out of desperate support for you. It's not an easy thing to do, no matter how in the right you are, and it's even harder to tell what the right thing to do--and the right way to do it--is when you're in the midst of it. Forest and trees; hindsight, etc. But you can do it. Hell, I grew up with a spine of linguini. If I can do it, you can!
Stay steely, Cap'n.
POD to all of this. Do not allow the team to decide the team dynamics. You are the Captain and should establish and demonstrate the team dynamics.
Take the lead in the pre-game meeting. State team policies.
1. Only the captain or co-captain can set mandatory training times and game meet times. Team members may set up optional training sessions as they would like.
2. No one subs out other players other than the captain or co-captain. If it occurs again, the captain or co-captain will call a time out or the team will be penalized for late start and the penalty will be on the person doing attempting the non-sanctioned subbing.
3. This is a recreational team only. There will be no trash talking to other team members. There will be no physical contact such as shoving of other team members. This behavior will constitute a 1 game penalty.
4. If any team member does not agree to these terms, we will understand when they choose to not return next season.
Unfortunately, dealing with the "Lukes" of the world (and their apologists, who in my opinion are almost worse) is one of the down sides of being in a leadership position.
At one time, I was one of the coordinators (so, one of the two people in charge) for a local non-profit event. We had one volunteer who was very enthusiastic, but was disruptive during meetings in the sense that he felt he needed to have input on every single decision, would insist on talking on every agenda item, and was extremely opinionated. And could get very huffy/hostile if someone tried to move the conversation along. Basically, due to this one person, meetings were taking three times as long as necessary (I wish I was exaggerating). And this is someone who was a volunteer, not a board member.
Now, I did basically like the person, and appreciated the enthusiasm. But he was antagonizing some of our other volunteers who were board members, and some other things. So my co-leader and I decided that we needed to address the behavior, and we scheduled a private meeting with the volunteer in question. We intended to discuss, as respectfully as possible, the behaviors we were finding problematic and try to help him understand what we wanted him to do instead.
Sadly, before the meeting could take place, he decided to badger me and the other co-leader (while we were at our paid jobs) trying to insist on knowing exactly why we wanted to talk to him, what had he done wrong, etc., etc.. And upon our polite insistence that really, we wanted to talk in person, screamed at me "I resign" and hung up. Which did solve the problem, in the sense that it made meetings more manageable and improved the dynamic of the group as a whole, but it wasn't fun at the time.
The one thing I've had to make peace with in my volunteer activities, particularly those in which I have a leadership role, is that there will always be someone who disagrees with whatever decision you make.
And there will always be those who, for whatever reason, won't or can't take on such a role for themselves, but who seem to take delight in criticizing or carping about those who do take on these tasks. It's best to acknowledge their existence, to sometimes review the arguments of those who disagree with you, as sometimes they may actually have a point, but to try not to take any of it personally (as difficult as that is, sometimes).
So yes, I agree with those saying that you need to have a firm conversation with Luke, and to be willing to take action to deal with his behavior, which is WAY out of line. It may or may not go well, but at least you will have made the attempt to be very clear with him about expectations and appropriate behavior, and that gives you the opportunity to take further action later if you need to.