Now I know that he was hurt last night so it doesn't matter in the grand scheme of things, but the real issue I have with Chapman last night was that the Cubs/Maddon are trying to make this "guy A pitches the 7th, guy B pitches the 8th, guy C pitches the 9th" every night and that's just rarely how it plays out. Take last night, after Wood walked Dahl, the score is 5-2, runners on first and second, nobody out, 2-3-4 due up. The game is definitely going to be decided in those next three batters. While Edwards is a good pitcher, this is a time when you need to use your best arm in the bullpen. I know Chapman would eventually give up the double to end the game but I think the game was lost in the eighth going to Edwards instead of Chapman.
But I agree that I'd much rather have Miller because I think he's as good as Chapman, has a better history of going more than an inning, has playoff experience, had more controllable years, and the Cubs would use Miller/Rondon interchagably in the eighth and ninth as matchups suggests instead of strictly one of them in the eighth and one of them in the ninth.