The Power of Sports is useful, But Overstated
I am a combat veteran of two wars and I found competitive sports useful to provide a distraction and work off excess anxiety and restlessness, but frankly there never was an Oscar worthy moment where the power of sportsmanship and football suddenly made all my problems go away. Military indoctrination, mental conditioning, and war trauma just really don't go away because you magically channel it all into a sports team. It's really just a pleasant distraction for a while that serves as a constructive way to burn off some negativity in a positive manner. I understand the misconception, too.
Most people have never been in a military unit, undergone any formal military training, or gone to war. The closest most people ever get to having a regimented and competitive lifestyle like that is sports, so it's only natural to think that if one could just channel themselves into sports that it only stands to reason that they would just be putting said conditioning and experience to good use and get over it. There are surface similarities, but a sports team and a military unit are worlds apart. Nothing the vast majority of civilians have experienced ever comes close to what being in war is like, so it's understandable that they don't understand the nature of combat, so I will give you a bit of an eye into the military mind and maybe you can form some more accurate conclusions from it.
They Will NOT Listen to the Coach If he is a Civilian
We have a near racial slur for you people. Civvies, or civs. A Civ is a soft, naive and docile thing that doesn't really understand hardship, sacrifice, dedication, or brotherhood. They either fear us, or are trying to get our attention by pretending to "get" us. When you are a vet hearing most civvies talk about the military is kind of like asking a 6 year old to explain what they think college is like. When you show up for a therapy session or for psychological counseling or even get treatments for a past wound and the person is a civvie it's pretty disappointing. You know one of a few things will happen. They will often come across as patronizing and simpering by trying to impress you with how much they "get it." Another thing they do is try so hard to tiptoe around the elephant in the room that it becomes annoying and awkward.
Finding out that the person you are meeting with is a combat veteran is a huge relief, because you can both communicate on the same wavelength. There is a mutual respect there as well as a shared experience. It is my advice that your coach be a retired very senior ranking enlisted man, who has extensive combat and military history. They will respect, resonate, and trust him more. He's not a "dumb civvie" talking about things he's never done or seen. He's one of them, he doesn't have to pretend he "gets it." It's just instinctively understood that he does without him having to undermine his own authority by being patronizing or offering advice on matters he doesn't have experience with. Being a previous senior staff NCO also generates a lot of respect because first, he's been a grunt foot slogger just like them who worked his way through the ranks just like they hope to do some day. It shouldn't be an officer, because the enlisted/officer relationship is too formal and would get in the way of the mentor-ship relationship.
It Should be Built on a Military Style Training Regimen
One of the reasons that sports might NOT appeal to somebody like this is because they lack weight. In the military nothing you do is pointless. It may seem that way sometimes, but the point is ALWAYS to learn some valuable skill, mindset, or achieve a better physical condition. When every action of your life is planned to make you better at your job and increase your survival depends on your ability to perform this job when you get back to the civilian world it's kind of weird. "Wow, these people really get worked up over something so stupid." When I run 8 miles it's because I need to make sure that I can locate, close with, and destroy my enemy. When I lift weights it's so I can carry a wounded brother better, or get a machine gun into position that saves my squad. "These people just do it because they want to put a ball into a basket better. How stupid and pointless." In the military as a combatant you do not just have a job, you have a purpose for existing. It is your sole purpose in life to either be winning wars, or training to win wars. These guys are going to just turn away from a purpose they were literally bred and born to fulfill to toss a ball? Not unless the training of it resonates. To do so it has to feel familiar.
There Will be no Magic "Oscar Moment"
I was not subjected to military conditioning until I was an adult, and I was a volunteer. I still have issues with a lot of stuff, including a recurring smoldering disdain for the often petty and trivial things that people always seem to get so worked up over. I suffer from an inability to feel much pity for much of anyone. In war weakness gets one or their brothers killed. Weakness is a sin and when somebody is trying to make me sympathize with them I often instead feel an irrational disgust and hatred instead. These are all issues I still deal with years later. These guys were conditioned from birth. They are going to have it even a lot worse than I do. It was never a choice for them, and they have very very little context to compare any of their experiences to that are not military in nature. Expecting them to suddenly be okay after winning a championship or something is just irrational. You need to set realistic expectations for these young men to achieve. They will probably never be totally alright. They can only really hope to learn healthy coping mechanisms and try to manage their symptoms. There will always be a disconnect there and there will always need to be a willful internal struggle to try to use the experience for good. It's been several years and I still sometimes have trouble. It's not about "getting over it" so much as learning to live with it.
Keep Them Separate from Normal Kids
Back to the civvies thing, except imagine somebody who has spent 15 to 19 years training to kill getting into a fist fight with a normal athletic, but mentally soft jock whose biggest claim to toughness is a few bloody noses and puffy lips in schoolyard scuffles. These spartan kids aren't really kids, they're honed killers. They are people to whom death is a suitable conflict resolution strategy. They're literally going to rip even your biggest "toughest" teen jock or bully apart. I'm talking broken bones, possible brain damage or all out death here. Introducing them to normal kids is going to be a very slow and gradual process that doesn't begin until well towards the end of the program once the members have demonstrated a clear and obvious improvement.
Summary
The sports are ultimately just going to be one tool among many that are used to ease these guys into a normal life. Don't expect all of them to make it, and even possibly expect some of them to actually wish to return to their old life, maybe even possibly do so. Hell, I actually miss Afghanistan and Iraq. I had a very simple and clearly defined purpose there and an easily quantified value and place within the hierarchy. I miss my brothers and I miss being so focused and having everything so clearly defined and understood. I imagine that at least a few of these kids will not see themselves as liberated and maybe even want to go back. The Sports Regimen could be a useful part of the recovery process, but it's not going to be the only one by far.