The fact is that this is a primary, not an election against Boxer, so it doesn't matter that they are all in a "dead heat" against Boxer.
The race is Tom Campbell's unless Carley Fiorina can stop him, Devore is not, and never has been in the race.
Carly is just about neck and neck with Tom Campbell, if you want Campbell beat, then she is the only route to that result.
That's your opinion. Not mine. What's your evidence of DeVore not being in the race? Ipse dixit? Feelings?