It sure seems that he's getting fucked, and not in a good way. If the difference is that significant, he should be looking for a better job.
I find it so unfair that at least in the NFL, the assistant coaches are NOT given any credit. Yet they put in more time and work than the head coach.
I personally know someone who has worked as a NFL assistant coach for 15 years and he has NEVER been given ANY credit for all the hard work and time it puts in. During the season there are days were he is lucky to get 4 hours of sleep - the rest of the time is focused on his work.
NO ONE ever talks to or about the hard work these guys put in. All this work is given to the head coach and HE gets all the credit.
Any one else feel this way?
With most pro sports teams, the assistant coaches are sort of encouraged to stay behind the scenes, on some teams they aren't allowed to talk to media at all.
The teams do this because they want to present a singular voice to the public, they don't want an assistant coach to say something that might be different than a head coach.
To be totally upfront, some teams have no problem letting assistant coaches speak to the media.
But, the by-product of assistant coaches staying in the background is that they don't get enough credit. (It should be noted that some teams close practice, so that no one even sees what they do.)
You're right, it is often a thankless job. A few assistant coaches make a name for themselves and get credit, but they are few and far between.
You raise a good point ...
in the public's eye, but whether it's the NFL, NBA, College, whatever, talented assistant coaches are definitely noticed by the people that matter, and are usually recruited to be a head coach.
I tend to follow college football more than the NFL, but look at USC as an example. Former offensive coordinators Lane Kiffin is now the head coach of Tennessee, and Steve Sarkisian is running the University of Washington's program. Both had the endorsement of Pete Carroll.
We have talked about it and he doesn't like dealing with the press. He has and does do interviews but doesn't like to, so he has always stayed away from going after the head coach position.
But I still would like to hear them talk about the assistants more during news coverages, pre game talks and such.
A lot of assistant coached don't want head coaching jobs. They don't like dealing with the press and the politics that go along with the job. They would rather be in the trenches doing the hands-on work and teaching.
Obviously, I'm not asking to see his check, but how well compensated are they relative to the guy on top? Any of those jobs are a mix of good & bad. He doesn't get credit for the hard work, but he doesn't have to deal with press. So, if he gets paid a LOT less, then I'll feel bad for him. Otherwise, it is what it is, and his choice is to deal with it, or move to the top job.
What he gets paid is A LOT LESS
Many head coaches get million while the assistants are lucky to get just into the 100,000 mark
So there is a HUGE difference.
I am going to assume he is not the offensive or defensive coordinator, but even if he has been doing this for 15 years, and he is the DB, Running Back, Linebacker, coach, he should be making much more than $100K. Not unless he is the strength coach. Not sure what they make.
Not to be rude but this is the problem, people make assumptions and think that the coaches make a ton of money ...well they don't - unless they are a head coach.
So how you know? Do you know someone or have done it personally yourself?
My knowledge comes from a dear friend that I have known for 18 years.
It sure seems that he's getting fucked, and not in a good way. If the difference is that significant, he should be looking for a better job.
Just like in any job you like to be appreciated and recongized for your hard work. And I think that assistant coaches do NOT get that period.
THAT was my point - it is not always about money.
So appreciate...coaches, providers, spouses, everyone 
no one talks about unless your a sports geek like me. Kornheisser et al never never ever give these guys credit. You are absolutely right, these guys do not get credit they deserve.