Anyone who thinks bunting can't be used as an offensive weapon needs to watch the Angels. Chone Figgins just in the last week has used the bunt to score runs. Laid down one of the prettiest drag bunts, with runners in scoring position, i have seen. RBI single and kept a rally going. In another game, batting right handed, pushed a bunt passed the pitcher toward the second baseman and by the time the 2B got to the ball he was already on first base. Both of those bunts were beautiful to watch.
Nice chart with scoring probabilities by Matthias. But, I think it misses the point. Would you rather your pitcher strike out, leaving a man at first with one out? Or even worse, ground into a double play? I think if more pitchers could bunt well, a man on second with one out is preferable to having him on first with one out.
There are situations where a bunt can be used effectively. I think a good manager knows when a bunt can be a useful weapon.
Just ask Mike Scioscia.