It's hard to single guys out on the team, considering they keep winning no matter who is out of the lineup. (I would have thought the drop-off from Chourio's injury would be felt, but the record doesn't show it.)
That said:
1) Contreras - I worry about a falloff in the post-season, given the number of games he plays - and plays through a significant injury - but he's one of the best players in the league at a premium position.
2) Peralta - When the pitching staff had more question marks than answers early on, he was the constant.
3) Collins - Didn't know what he was doing on the team in April and May. Since then, it's hard to imagine this team being where they are without him.
4) Megill - Even if Devin Williams hadn't imploded in the Big Apple, we replaced an All-Star closer with...an All-Star closer.
5) Frelick - I don't know that the team's maximum-effort mindset comes from how he plays....but I know they didn't have it before Sal established himself.