JUPITER, Fla. -- Deciding that they needed a long reliever more than another late-inning flamethrower, the Cardinals optioned Chris Perez to Triple-A Memphis on Monday. The move leaves 12 healthy pitchers in camp, effectively setting the St. Louis pitching staff a week before Opening Day.

The Cardinals elected to carry long reliever Brad Thompson on the season-opening roster, a move that was admittedly as much tactical as it was any reflection on the overall merits of Thompson and Perez.

"It comes down to that extra pitcher, we need innings from that guy," manager Tony La Russa said. "I'm sure [Perez would] rather pitch in the big leagues, but he knows he's highly regarded, and he's young, and Memphis is not a bad situation."

St. Louis will take seven relievers north: righties Jason Motte, Ryan Franklin, Kyle McClellan, Josh Kinney and Thompson, and left-handers Dennys Reyes and Trever Miller. Most of those pitchers had their spots sewn up relatively early in camp, but intrigue remained over the final decision. Perez did nothing to pitch his way off the Major League roster, though a two-week hiatus due to shoulder discomfort didn't help his case.

"I wasn't really dominating before I got hurt," Perez said, "so who's to say how it would have gone those two weeks? But it would have been nice to stay healthy and have an even better shot. But it is what it is."

In light of Monday's move, the distribution of duties in the St. Louis bullpen also is becoming clearer. Motte will factor prominently in the ninth inning, though La Russa and pitching coach Dave Duncan will not announce a designated closer before the season starts.

"We're going to use whoever is available," La Russa said. "But I would believe that Motte will get a chance to close games."

Both Miller and Reyes project as specialists. Each of the two lefties is best utilized when his exposure to right-handed batters is kept to a minimum. Franklin projects as the primary right-handed setup man. Thompson will be a long reliever, while McClellan can fill a variety of roles from pitching long relief on occasion to pitching late in games with a lead. Kinney, meanwhile, appears to be in line to take the job held by Russ Springer the past two years. He will be the right-hander most often called upon mid-inning, with runners on base.

Kinney did just that on Sunday and Monday, pitching on back-to-back days for the first time since 2006 -- before he underwent reconstructive elbow surgery. Both times, he escaped without allowing an inherited run to score.

"I think he's suited to come in to start the inning [also], but it's a unique thing," La Russa said. "Russ Springer was outstanding for us. When [Kinney] is available, when that situation arises, he's probably the best suited for it."

The question was long relief, and it was a significant concern for the Cardinals. So although Perez pitched well throughout the spring, the call was made to keep Thompson on the roster and to send Perez out. Only one St. Louis starter has thrown a pitch in the seventh inning this spring. Compounding that is that the Cards have an unusual early regular-season schedule, with just one day off in the first five weeks.

That combination led to a strong desire for a reliever who can pitch multiple innings at a time.

"If [the starters] have a bad game, you can blow your bullpen in one or two of those games, and use all your relievers," La Russa said. "You need an innings guy. Or two."