I think if I have understood them correctly Stephen Travis and Tom Wright are presenting a model of the atonement in which Christ is suffering the consequences of our sin, he isn't being 'punished' for our sin. God allowed people to experience their life as alienation and Christ does not die to avert God's wrath but he restores people to God who is grieved that they are far from him and wants to be reconciled and so all of the sin exhausts itself in Jesus Christ. We must be careful in describing atonement as penal – our primary thought must be not God's wrath but his triumph over sin – the wrath of God is not retributive but preventative.
All the evil converged onto this one point - onto Jesus Christ. Jesus Christ on the cross defeated violence. He disarmed the principalities and powers – God wanted to liberate the whole of creation and so he exhausts evil, he has it all dealt with by Jesus Christ.
Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross; And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.
If we take Penal Substitutionary Atonement alone and out of its biblical context – then we have a warped view – we need instead to see PSA within the framework of a victorious view of God.