Question

No, you're not wrong. When you buy what somebody's selling you want them to have credibility, to know that what you're getting has worked for them.

By the same token the best coaches don't always win, and even guys with average-mediocre records may have a lot to offer.

One of the best clinicians I ever heard was Jim Walden, the former Washington State coach (1978-86) whose winning percentage there was .460.

Guys who are better at using technology to create media than coaching their teams perhaps.

Good observation.  I have a lot of agreement with you.

I suppose that in every profession there exists  those who truly are pro's, and then are many others who just read books and think that it makes them an expert...that type NEVER miss a chance to tell you that, too!  notice the CAPS LOCK?

Talking the "talk" is easy.  Some people will purchase anything that's in print, and there are coaches who know that...so they print stuff.

Nevertheless, any ideas that someone may have are probably worthy of at least, some consideration.  We all "borrow" stuff from each other and tweak/twist/ or otherwise modify things to fit our own way.

So, you may never adopt everything someone else did, but you might take something from it.  I have actually "borrowed" simple things like nomenclature, or snap counts, hole numbering...calling motions, etc. 

Perhaps "credibility" is in the eye of the beholder?

Exactly! This is the worst part.

For example, a DC I follow released a bunch of clinics tapes from his system and has yet to back it up with results. And then, I browse my timeline and other coaches are calling him a genius and a guru. I’m just sitting there thinking, man this dude hasn’t had a winning season since 2010 and people are making him out to be a messiah. 

Oblivious coaches are buying that stuff without doing any fact checking. Totally bothers me. Like, cool you put a fancy PowerPoint together with cool pictures about your scheme, but are you winning?

Sometimes a 2-8 team takes a he'll of lot better coaching than a undefeated team.

This does get under my skin. There are several high school coaches on social media peddling existing offenses and are marketing them as their own. One has a free "chalkboard session" where he draws up various schemes he's been tinkering with. I've found three YouTube videos of the exact schemes he's discussing, run a decade and a half ago, and post them in the comments.

To be fair, it appears as if the guys know their chit and are selling a comprehensive package (Xs and Os, install guides, drills, etc..) but give credit where credit is due.

Social media has made it really easy and cheap for people to market themselves as some kind of guru. Check out Twitter strength & conditioning. It's a cesspool of dogma, ad hominem attacks, faulty conclusions, and ridiculous exercises.

The problem is that there is a market for this garbage. There are way too many people who don't want to do the hard work themselves. It's just easier to buy something online.

Great job of evaluating the source of information- This was always emphasized when I was in school but seems to have been overlooked by some.

As always, Buyer Beware.

I find that if you just reach out to really successful position coaches, they are willing to talk ball and share details (because they love teaching the game to anyone who will learn).

Lots of people just want a magic bullet.

My kid had a really great high school career. 10 varsity letters, 4-year 2-way varsity football starter, 1st Team All-Stater, etc, etc. He was also a competitive powerlifter who broke several world records for his age and division. I would get emails often from parents who were really impressed with Eli and wanted to know what program he was using, nutrition, supplements, etc, etc to get where he was at. So, I would tell them the following:

1. He lifts 2-4 days a week and typically does 8 sets of 3 reps on the big lifts (squat, bench press, and deadlift) and tries to get about 50 reps on 2-3 accessory movements.

2. He gets at least 8 hours of sleep every night.

3. He drinks a gallon of whole milk every day and eats big and relatively clean.

4. He never skips training sessions. That means if he doesn't get home from wrestling practice until 7pm, he's getting a quick meal and will be in the weight room by 7:30pm.

When I would share that with the people who asked me, they were never impressed. They simply could not believe that a high school kid could make such incredible progress by following such a simple plan. They wanted me to give them some super-secret cutting-edge program with bands, chains, wobble boards, Bosu balls...that kind of stuff. I would even offer to allow other kids the option to come in and train with my son. None of those kids lasted more than a couple weeks. The hardest thing for those kids was committing to the consistency. And consistency, not some combination of sets, reps, and crazy exercises, was what led to my kid being an elite high school athlete. 

But people really didn't want to hear that. 
 

The disconnect that most people have is that they think easy and simple are the same thing.

Most are defeated long before the battle has started. What is not simple or easy is the discipline. Most task, jobs, goals in and of themselves are simple and easy. Where it gets ugly is when you have to make choices. 

Yes, I think you're wrong.  Someone might be selling or preaching something that hasn't yet worked in their hands, but could be made to work in somebody else's.  Caveat emptor applies, and what you find out about records, others may find out about records too.

But records don't say everything.  Somebody may have something particularly good that's balancing a particular weakness they have.  Like, if they weren't doing that, they'd be awful instead of just bad.  Or it's something that works for some players but not all.  I have a drill that worked great with the first bunch of players I tried it with, but the following 2 seasons with different players, they just didn't "get it".