Alex I don't think your backup is good enough to really be a good backup at the GHL level. He is a really good overall goalie regarding his skill set but 86 reflexes is bad when a lot of the shooters facing you have 95+ shooting.
This is because a number of managers resign pretty much everyone on their roster, usually until they get really old, no matter their actual performance. It is, frankly, a stupid practice. If your team has issues why are you going to keep bringing back the same players and the same team and expect something different? If there is an issue with the performance of a player trade them or let them go when their current contract is up. I don't mean to bad mouth Erzac but his team is a prime example. After his S1 championship his team has been struggling to get the results despite the talent. At what point do you stop banging your head against the wall and accept that you need to change up the roster in some way? You don't have to go chasing 'better' overall players to get better results either. If I had his team I would have turned over almost the entire lower half of that roster a season ago because many of them are just playing poorly for whatever reason. Too many managers get too overall focused and also get too locked up in the team that they have.
As for your goalie issues, I think it is down to a lack of endurance in both goalies. Your backup is actually playing rather well on the whole. When both goalies have low endurance giving adequate rest for your starter is quite difficult when the backup has an occasional bad game. When my buzzer team was in its second season, down in the IHL, my starter and backup both had low endurance and a chain reaction happened where both goalies ended up yellow tired. Both of them got hurt in the next game that they started. In my opinion, finding a goalie you wouldn't mind splitting starting time with Amick would be the way to go. Try to get a two goalie system where your second goalie has more endurance and can play a few extra games like what I have with Wilcot.