John Smoltz was a consistent starting pitcher with a Cy Young award to his name. He then made the successful transition to reliever (and was one of the best relievers in the game). This switch was very reminiscent of Dennis Eckersley. However, one distinct difference was John Smoltz is one of the greatest postseason pitchers of all-time (check the stats if you think otherwise). All these combined elements make him a first ballot Hall of Famer.
As for some other pitchers who others think are on equal footing with Smoltz, they’re not. Schilling will never get in because he was never consistent (he had about five,six good seasons spread apart). His totals don’t add up either. And Mussina will never get in because he never did anything spectacular in his career (no awards, big playoff wins, a big win down the stretch). Being from New York, watching Mussina pitch in the postseason was agony (aside from the ‘flip play’ game against Oakland). He would either: give up a couple runs right off the bat or give up runs right after he was spotted a lead. As Michael Kay so accurately put it, ‘He pitches good enough to lose’. Amen.