He will continure to struggle unless he changes things, he is mentally and physically ill and drained. He is not too old, and can still compete on a world level if he gets his act together. Here is what I suggest.
1) take 2 weeks to a month completely off distance running, and do not even spend time thinking about running during this month---he needs to mentally and physically refresh
2)start back by playing other sports that involve running ex. soccer/basketball, lifting weights
3)gradually cycle into running again, starting off slowly with no expectations
4)build a consistent running base, touch on speedwork and lift weights for explosive stregth regularly
5)get into regular running workouts, tempos, 600-1k reps, XC type stuff
6)do a couple races to have fun, ex. XC race/road race/obstacle race
BUILD CONFIDENCE
HAVE NO WORRIES
MAKE IT FUN
NO CONCERNS ABOUT PERFORMANCE
LET THINGS FLOW NATURALLY