As a Cards fan I'm so-so about this. I think he can help, but only in a limited role and if he turns things around from earlier this year.
Duncan can work wonders, but maybe not this time.
I was up in Boston earlier this year, and I got to see Smoltz throw against the O's. It was brutal. Every time an O swung, you heard this "CRACK", often followed shortly by "POW" of the ball hitting the OF wall. The outs he did get were mostly hard hit ground balls and line drives. It was brutal watching one of the more prolific pitchers of recent years struggling so mightily to get outs.