Is this a good fantasy baseball trade?

Depends on what you specifically need on your team. Gregg isn't very good, and Baltimore won't give him too many save situations. Sandoval is having a good season, but can be an injury liability. As for Team B, Quentin's .260 AVG is a disappointment, but his 17 HR puts him as one of the top power hitters in baseball. And Romero's having another solid season (2.98 ERA), but his record (6-7) doesn't show it, since Toronto doesn't give him too much run support. Ultimately, I'd say Team B is getting the better deal, but like I said, it really depends on what your specific team needs. Hope this helps!