His career numbers actually show that one extra day of rest makes 0 difference. More than one day is a big difference, but if you look in detail you'll see that most of those are either after the all star break or an injury when he has 10+ days of rest. In addition, this tells us nothing about whether or not extra days off have any effect on future games, which is really what matters here. I was all for him coming out of that game after 5, but not adding days off.