Hey "readers..."
What you say about Dellingers flaws are correct. All coaches have flaws. I whole heartedly agree with your analysis and am thankful you wrote it in a respectful (not bashing nor hateful) way.
Back to the point. Why did Nelson fail under the Oregon program? It's not totally Dellingers fault. From my understanding it was both the coaching style (meat grinder/non personal) and Salazar. Yes, Nelson got injured but it was a conflict in his running mentality and Oregon's. Nelson ran for fun. He wanted to enjoy his experience, enjoy his team mates, etc. Salazar wanted to show Nelson that Nelson wasn't $hit so he thrashed him at every workout (now to Salazar's credit, his huge ego did this to everyone coming into Oregon, so it's not like he was actually picking on Nelson or singling him out). Nelson didn't like the competitiveness Oregon had (Salazar) and so he left for a happier place. Now this isn't written in stone. I've never spoken to Nelson personally. This is second hand knowledge and may be off but it is what I believe happened to Nelson.
Dellinger definately allowed the hostile team mates ego's beat up the newbies without a blink. He definately didn't make freshman feel welcome. Sure if you are a Salazar, Cruz or the likes I'm sure he gave those guys a descent welcome. But to everyone else it was just "here's the workout" and would throw you into a workout designed for a 28:20 guy and you were expected to run with that guy. When the 18 year old freshman couldn't hang with the Senior All Americans Dellinger would basically shun you, telling you that any freshman should be able to run 14:00 with proper training.