Yes dump him. However, I am going to disagree with Arlo, and suggest Carlos Hernandez. Look at his game logs. He is pitching very well, he just isn't getting the run support. He is guaranteed a rotation spot. Soriano has the skill, but he is under the microscope with his starts.
I would go with Hernandez at first, but keep an eye on how Soriano fares. But Hernandez will give you some consistency.