In my view the effectiveness of the art (any art) is a combination of the individual, the curriculum and the training methods
The curriculum provides excellent techniques for fighting (as well as some not-so-useful-nowadays techniques)
The training methods are very variable from one dojo to another - this is an unfortunate reality that, in my view, results in our inconsistent reputation amongst folks on here
One of the most senior teacher's in the UK, Peter King, has posted about this on his facebook page. He was a police officer in one of the most violent parts of London for 30 years and has a medal from the queen for taking a machete off someone
Back in the day a few Bujinkan folk did compete in MMA - one example is online here - But they are few and far between and to be honest if you want to compete in MMA then you'll be more successful studying MMA than Bujinkan (very limited ground work in Bujinkan, gloves screw up a lot of the techniques etc etc)
Case and point bujikan had a ninja phase and used that to try and sell itself until ninjas got mocked to high hell and back.
Effectiveness is one thing, how you sell it is another. If you sell anything as a martial art there needs to be some, and at least good martial application. (which can be quntifiblae and objective)
Then you just lay down criteria and create something that meets your criteria. (marketings relation i will get to) the criteria can be wrong, thus the martial art is bad. but if it meets all its crtieria its not bad in a implimentation way, just it was made for things that dont happen.
I dont know the wording to distingish between something poorly designed or just wrongly implimented. For example, if you included hip throws for a boxing school, thats just wrong and pointless for boxing, yet the hip throws could be taught right and work.
Onto marketing, if you shove say self defence on it, you NEED to provide the education you say you do by shoving self defence on it. If you claim your art is for "street fighting" then it MUST work outside of comptetiton and sterile enviroements, and must be competitive to be called good. If you sold it more as "tradtionally techniques of the X" and there was no implied* it working well or being designed for modernity etc then i can get it. (although a punch is a punch, thats as far as i think HEMA and other historical arts work, if you get your hands on say a longsword your good to use it if you need to, and a punch is a punch)
*some people do try to sell these as modern martial arts that work, or imply they do, sort of in the realm of my bracketed point, i dont have a issue with the logic a punch is a punch, but some go over that. Without examples cant be specfic but i think that gets my point across. although the logic of learning to use what you have is also present, so if you plan on using a Katana, well Kendos a sport, so some other system may be for you. Thin line is all i can say, id need to break down a specfic system and keep it case by case.
the bulk of complaint is as i said, martially inspired dance is sold as a martial art, in other words something thats not fighting is sold as techniques FOR fighting (this is from reasonable people who understand the diffrent dimensions and some about hisotrical preservation etc)
You are going to suck in MMA unless you do MMA, nothing is MMA apart from MMA. Your going to suck if you are a sprinter and try to do distance running, or vice versa. But the fact is, the tradtional combat sports of Muay Thai, Boxing, Judo, MMA etc, seem to work pretty well outside of their respective sports, so that at least speaks to their training methods/content of the sports.
i dont think enough information is had to put the tradtional japanese training methods in comparision with the modern sport ones. although how the same arts did it back in the day is diffrent to how they do it now, as far as i recall pretty much all jujutsu schools did free sparring, and actually properly fought each other as routine. (i may start a thread on that)
Addendum: We also have to assess what the teacher has done and what he teaches you, like he could be fairly good at fighting, but not teach you half of what he actually knows that he picked up from say 4 diffrent styles. Like some people do other styles and dont teach the other ones they do yet still practise them, and that influences them and their ability(not yours). It would be like being a black belt in Judo, teach boxing and because you were able to pin somone means boxing is vaible in judo, no it means the person who has done judo is viable in judo.
Addressing the machete point, many constables have disarmed people, many have died doing it, and this is a very varied martial arts experience. Id need to see some footage to assess if it was luck, his ability or the persons inability. there are many biases that surround here, confirmation trhough survivour bias is a big one. ie this worked before so should work, while ignoring the opponent was just severaly undermatched, or screwed up many times. I dont think Bujikan would have addressed how to use a baton, taser or OC spray though, or how to restrain somone in the manner policy dictates, so that probbly came from his police training. (another complaint, these things exist yet martial arts skirt around them for legal reasons, lest they be accused of paramilitary training, at least one reason or not wanting the politics of weapons control brought up)
That sort of ties in with the above, but i sort of clinged to one general point instead of the specifics, and dont want to have to rewrite this or spend a hour, im dropping the ninjutsu argument though as its sort of besides the point, i have put enough across to show its disputed.
thats my thought process anyway, but if the teacher has done judo, and is good at it, it doesnt mean he is teaching you judo. Case and point i think one of my TKD teachers did Judo, so it would be used if he ever fought (pending retention) but he didnt teach judo, so he could whoop you in a grappling match potetionally but hes not teaching you to do it. That doesnt invalidate the complaints of lack of grappling in TKD or TKD is not built for it, or does it. It isnt and doesnt. See i am at least trying to be crticial here, you can say many things, this not being thought out isnt one of them.