Against AL EAST:
Boston: 2.88 ERA, 34.1 Innings Pitched
NY: 6.45 ERA, 44.2 Innings Pitched.
Jays: 4.45 ERA, 58.2 Innings Pitched.
Rays: 3.32 ERA, 62.1 Innings Pitched
Averages out to a 4.28 ERA against the AL East. Of course, a pitcher does not only face against just the AL East.
Greinke had some terrific years for KC and he has been well worth a 100M contract with his work in MIL. If you base off FIP
and xFIP, Greinke has been one of the better pitchers in the league the past 2 years. Even if you go back to his FIP and xFIP
from his American League days, they were still low 3's. I see no reason why Greinke wouldn't be a good acquisition (barring an extension). Let's be honest, the Orioles have the money to spend, they also have a lot coming off the books next year with Gregg, Reynolds, etc.
I know someone is going to say something about his ERA against the Yankees, but EVERYONE sucks against them. They are the Yankees for a reason.