Bradley is definitely our best player and needs to be on the field for every minute of every game. Our ceiling with Bradley playing well is higher than our ceiling with any other player in his role. Besides, I don't know who you put in midfield -- you could put Dempsey in the middle I guess but he's probably needed further forward with Altidore injured. Zusi is better out wide, Beckerman and Jones are both more defensive, you don't have anyone who could be the linchpin of the attack in the same way Bradley's capable of. Diskerud is probably the best bet but I wouldn't trust him over Bradley.
I think we have to live and die with Bradley, there's just no capable replacement.
It does suck that Holden has been injured, he would be capable of playing the same role if he'd kept improving, and probably would have been among our best players. I'm amazed that Bolton offered him another contract, I'd be surprised if he's ever really healthy again.