I see nothing wrong with giving him days off. But you can't deny that he's been scuffling this year. The only thing that matters is production, correct, and his OPS is at a career low at .832. I fully expect him to improve, and giving him days off could very well make this happen.
And I don't think anyone here honestly expects Smoltz to dominate right off the bat. He's not going to be as good as he was in Atlanta for a number of reasons: injury, age, change of leagues. We've accepted that. He should still be a productive pitcher, and he'll add to the depth and improve the team. Don't put words in our mouths.