I'm surprised with so many people commenting "it's just 5 hours". It's never just 5 hours. After the game finishes he will most likely be too tired to do anything active with the baby.
Also 5 hours is almost another full day not at home, which the mum will have to pick up the childcare. The mum definitely can't pursue her hobby on Sunday unless they don't want to do anything together as a family. It's the husband living his old single life when the wife is sacrificing her time for his enjoyment. Their baby is young and she needs help.
Having said that, the husband sounds like he pulls his weight during the week. So good on him for that.
Reality is, the less time the husband spends with the baby, the baby will become more attached and reliant on the mum. That is something your husband will probably notice his son is more distant and will be his own wake up call to take on less games on his own terms.
To avoid resentment, start scheduling things you want to do and ask that he looks after the baby during that time. Might be that he looks after the baby after work and you go out with your girlfriends. Go out for a nice walk and breakfast on the Saturday and have your friends over your house for afternoon tea when he's gone.
It is much better for him to realise himself of the time sacrifice with his son. Sometimes they get a wake up call when they see someone else doing it. My husband realised he has a problem scrolling his phone when he's looking after our son when my brother was doing it. I've been telling him for a while but it's not as effective as him seeing it himself.
Or plan for a nice weekend road trip holiday once in a while so it will be a full weekend adventure.
Good luck.