The two earned runs from last night were charged to Harvey, the one run from Saturday was unearned, and the one from game one was the only earned run of the series. So one earned run in four innings pitched does translate to a 1.80 ERA. But it's the three blown saves that is the kicker.
I dug a little deeper, and even though the World Series is a very small sample size, it looks like Familia was better statistically in the World Series than in the regular season by almost every measure except for the blown saves (ERA, hits per innings pitched, etc.). Go figure.