You definitely have enough speed to make a trade for some better pitching. I would drop Robertson regardless of whether you make a trade or not. He will be a long reliever this year unless their are some major injurings. Plus, Carlos Hernandez will probably be lurking at AAA just waiting for a chance and he has a better upside right now than Robertson. You should be able to find better FA option, Jerome Williams, Peavy, Penny for eg., than him.