I'd say there is a small part of it the Week 2 difficulty spike that's due to that - if you check his stats, whilst he's not massively ahead in attack or defence compared to the newbies, his HP is far ahead of the new trio, so I think losing his HP pool from your team's overall HP is much more noticeable as a result. Combined with some trickier battles, I think it's a lot easier to die in early week two as a result.