"What's the most important trait for a coach?"
A common question in the fitness and performance industry, and a rather vague and variable question depending on who is answering. I've seen this question asked and answered time and time again, and some of the most common answers submitted are usually that of "open-minded" or "constantly learning" or something along the lines of always trying to increase one's breadth of knowledge and understanding. For myself, I've thought quite a bit on this without answering too often, but I think that there's an underlying trait between that category of answer, and great coaches, and that, is Nuance.
Nuance is seeing the subtle difference or implication of things; realizing that usually there is no simple answer to any complex question. Even my first analysis of the question, "What's the most important trait for a coach" was nuanced, recognizing that there can be a lot of different answers. I believe that constant self education is highly important for any professional, no matter what the field; constant updates in information leads to small or massive changes in procedure, such as when physicians realized that washing their hands before operations led to significantly less deaths in their practice. This is a more extreme example, but you get the idea; even though the information at the time said that 1-2% of deaths were supposedly related to hand-washing and changing the practice wouldn't change anything, it actually would. The people who fought against hand-washing were highly educated men (being that most practitioners at the time were men) but they were not very open-minded.
Open-minded people can listen to everyone and consider the possibilities, but this can lead to people either being too willing to try new things at the expense of progress. I'll take myself for an example of this; I'm still very open-minded (or at least I like to think so) and it's helped me make some progress in my athletic and professional paths; but unfortunately I found myself too open-minded, and was eventually paralyzed by the inability to create an effective system for myself. In the case of my athletic performance, when I first started competing in Olympic Weightlifting - I was willing to try plenty of diets to help me drop weight to a more appropriate weight class, being that I was severely overweight, and could do with dropping some body fat anyway. I tried lots of things, and even though it's embarrassing to admit at times, this included gimmicks like Bulletproof Coffee, Carb Backloading, Low Carb Diets, and even Keto Diets, to help me improve my performance in Weightlifting.
To be clear before anyone goes off the rails here, I am NOT saying that these methods are not effective means to an end; what I am saying is that they were not effective for me, someone trying to cut bodyweight while maintaining high levels of performance. These can be effective strategies, if you understand the underlying principles of dieting (energy balance, individual macro nutrient needs, individual biological and/or health issues, etc).
Although these diets helped me lose weight initially very quickly, I found myself struggling excessively to perform well; in fact, I bombed out of 10 straight meets in a row because I didn't have the energy to perform at the necessary level. It was only after a year of adamant adherence to these protocols, did I start to think, "Maybe this isn't working out," and I had to seek other avenues for dietary help. However, this doesn't mean that these protocols don't work for others just because they didn't work for me.
There are plenty of people out there with their own tales of how CBL or Keto works for them and they can perform at levels that satisfy their needs, even towards national or international, and even Olympic levels of performance. This doesn't mean that these diets are the new solution for unlocking higher levels of human performance, nor does the literature dismiss it as folly either. In reality, all diets work if they supply you with necessary energy for basic biological functions, macro and micro nutrients for balanced health, and a feeling of satisfaction that leads to you continually sustain the lifestyle and goals you are seeking.
These principles also apply to training methodologies as well; I've had a few different coaches for Weightlifting over the years, with different coaching styles and programming styles. I benefited from something from them all (more than others) and I've also had detrimental experiences with all (some more than others). However, the coaches that I benefitted the most from over the ones I benefitted the least from were and are those who are able to look at my personal situation - training environment, training age, access or lack there of to certain equipment and exercises, etc. - and adapt the plan needed for me. The most successful coaches that have worked with me, not just in weightlifting, but in my other athletic endeavors, are those who can look at me, and others, and go "Ok, maybe this plan isn't working, let's try something else," even when I was in the same environment as their other athletes.
The coaches who are willing to look at an individual from situation to situation and adapt a plan for the athlete's benefit vs building up their personal methodology, in my opinion, is the coach that will have the greatest success in their career. It's very, very, VERY easy to get set in your ways, and to have a personal bias that will make it so that even if you are constantly educating, and open-minded, that you'll inadvertently take the information and twist it to build up what you're already doing, rather than add a new tool to your tool box. I think that the ability to say, "Ok, this way of doing things that's worked for 99 athletes isn't working for this 1 athlete; how do I work with this athlete to achieve their goals?" is far superior than saying "How do I make this athlete work under my system."
A coach's system should only be that to constantly improve the athlete under the athletes terms; not every athlete wants or can thrive under a singular methodology. This goes beyond a coach just saying, "Hey, my squat program isn't working, but Coach over here does this, let's give it a shot for you" to maybe changing the entire paradigm of your program for an athlete. There are some athletes who can thrive and get better under immense amounts of volume, but can't improve no matter what under low volume and higher intensity training. There are some athletes out there that, for the life of them, can't handle even moderate volume without dying, but for some reason, can have herculean strength when just doing heavy singles in the Olympic Lifts and Squats and nothing else. There's also athletes that float somewhere in the middle, and at times thrive under just good old fashioned work, and after a while, thrive under going heavy regularly.
The ability for a coach to read the needs of athletes from case by case, and adapt the plan accordingly when the situation requires it, is far greater than the coach who knows the literature as if they had photographic memory, or the coach who's willing to find the value in everything presented to them. It requires a lot more time and effort, and can be tedious to write out a new plan every time it is needed, but the question is, how much does the coach value the performance and success of the athlete or client, vs creating their own methodology? As a side note, it's also far more enjoyable to interact with people who are willing to see the nuance in a situation, vs those who constantly try to validate their point and beliefs (trust me, I was the arrogant little ass who argued CBL as the word of God, and people find me way more enjoyable now that I don't mandate drinking butter coffee over everything else.)