Chris Carpenter knows today’s drill for the Cardinals’ home opener. He’s done it 10 times before. Wake up, gather the family and head to Busch Stadium. That’s where a bright red or white car or pick-up truck will be waiting to chauffeur him around the warning track. Today is a civic High Holiday. Fans lean over railings to scream their hero’s name and maybe reach out to touch. Sometimes it might be a bigger deal to those in the stands than those in the cars. Today will not be one of those times for Carpenter. This afternoon’s drive will wheel Carpenter within the current version of Busch Stadium for a seventh time, probably his last time as a player. “Part of the reason I’m looking forward to it is, I think, is because it’s going to be the first time I’ve put on a uniform since I took it off in San Francisco. It’s weird. It could be the last time,” he says. “It’s a lot of fun. It’s a great experience to be part of. I’ll take it in a lot.” Carpenter hasn’t thrown a ball since the first Friday in February. That was the day that forced him to make one of the most difficult phone calls he’d ever made — to tell Cardinals general manager John Mozeliak he couldn’t pitch any more. Mozeliak recalls the emotion he heard on the other end of the line. Two months later Carpenter still speaks haltingly about the situation. “It’s been hard. It’s been different,” he says. Pausing for a moment, Carpenter then adds, “It’s definitely been hard.”