One question that I did have, and I hope this doesn't take us off topic, was "Is this true for EVERY sport?"
There was a thread on here awhile back that got to a not so serious point where someone said a football player could be recruited while reclined in a lazy boy, in his living room, with his shirt off, potato chips crumbled on his stomach, playing a video game and not even looking at the coach and get a full scholarship offer but for a baseball player you are totally screwed if you have your hat on backwards.
The article seemed to address multiple sports, but is that really true?
I think it is true in every sport to widely varying degrees within each sport. For baseball, specifically, my experience is quite different than what you describe. The very talented are likely to get offers somewhere provided they are getting sufficient grades that will get them accepted. The behavior and all the other characteristics addressed are factors but not necessarily deal-breakers. My son, his playing friends and past players I have coached have had plenty of first hand stories to tell about college teammates that check several of the red flag boxes mentioned in the open letter but were talented enough to be recruited anyway. The coach/writer is correct in the sense that in almost all cases, these players continue to be a "challenge" to deal with at the college level. For some, it eventually affects playing time and/or sticking with the team. For many, they continue to play but are team cancers.
I think, generally, the top D1 programs can afford to be a bit more selective and many of the smaller schools will allow for character to rule the day, but everywhere in between, the pressure to win and to put a talented team on the field factors heavily in the equation. Of course, as always, there are exceptions.
The coaches are very likely to inquire and, certainly, will choose the high character kid over the other when comparing equal talent but talent is never truly equal from one player to the next.
There are some interesting dynamics in play with this discussion. We're talking about 16-19 y.o. teenage boys. Most have been praised and/or given passes here or there due to their above-average talent. Most have that competitive edge that helps them excel but also often results in an air of confidence that can be perceived as something far from being a humble servant.
It will be interesting to hear other takes as I'm sure they will vary. Admittedly, much of my first hand experience is with competitive JC's and D2's where I would expect the likelihood of a bit more tolerance. However, I also have several past players in Christian NAIA's and D3's who have the same experiences and issues, although generally on a lesser scale.
The good news is that the message is still well worth sending and will serve a young man well, regardless of how it does or does not affect his fellow teammates.