He got too much criticism? I don't think he got too much criticism at all.....IMO the issue was could he take any criticism, could he learn from the criticism he got....those IMO are the real issues. What was the bad rap he got.....this kinda sounds as he was not treated well there......total BS.
IMO instead of having a chip on his shoulder he should buckle under and keep in mind that his position is a "learn something everyday" type job and what you did poorly yesterday improve on today. Saying he has a chip on his shoulder to me means he did not garner any of the criticism he got and he's going to prove that criticism to be false.
To improve on the issues he had/has he needs to own up to them, except them and move from there, not be PO'ed about being criticized.