Guys like Matusz and Arrieta could really blossom in San Diego. The Padres need a shortstop but I can't see trading Machado. He's three weeks past his 20th birthday, for God's sake.
Jonathan Schoop is the Orioles' third-rated prospect and, like Machado, he was signed as a shortstop. Like Machado, he's 20 years old (21 in October). But, also like Machado, he's unlikely to see the big leagues before September of next year at the earliest.
I think Headley would be a great fit... an accomplished third baseman with power and an ability to get on base. We simply don't have anybody like that.
Let's try this lineup for next year:
1. Markakis RF
2. Headley 3B
3. Reimold DH-LF
4. Jones CF
5. Hardy SS
6. Wieters C
7. Davis 1B/DH
8. Avery LF/some backup catcher
9. Quintanilla/Flaherty/Adams/Roberts... 2B
Baltimore has a backlog of possible starting pitchers... Tilliman, Arrieta, Matusz and Berken are only a few of the names that might follow Chen, Hammel and Britton in next season's rotation. Whoever starts would benefit from better defense and run production. That's what Headley would bring to the table.
I'd offer two starters, a minor league reliever (Schrader?) and Jonathan Schoop for Headley and see what they say. I'd do that today. :)