MIAMI - And so the thin get thinner. The concerns continue to mount.

At a time of the season when they should be gathering momentum for a postseason run, the Phillies are springing leaks in some of their most important areas.

A slew of relievers are hurt, and one of the healthy ones, closer Brad Lidge, now seems hopeless.

On top of it all, Carlos Ruiz, their invaluable catcher, is having trouble shaking a left wrist injury he suffered last week.

Ruiz spent yesterday in Philadelphia, having an MRI that showed swelling but no structural damage. He is likely to have a cortisone injection today before rejoining the club in Milwaukee, where it opens a four-game series tonight.

Don't expect to see Ruiz in the series. General manager Ruben Amaro Jr. said Ruiz would need to sit for three to five days after the injection.

As far as Ruiz is concerned, the Milwaukee series isn't a major concern. Despite another blown save by Lidge (No. 11) in a 7-6 loss to Florida last night, the Phillies remain on course to clinch their third consecutive National League East title, and they can get it done with backup Paul Bako behind the plate.

It's the postseason that would be worrisome without Ruiz. This is a guy who caught every game of the postseason last year, a largely unheralded player who has gotten better and better this season, forming a tight bond with the pitching staff and swinging a pretty good bat lately. Phillies officials have their fingers crossed, hoping that relievers Scott Eyre, J.C. Romero, Chan Ho Park and Brett Myers can make it back - healthy and effective - by the time the postseason starts on Oct. 7. Now they can add Ruiz's name to the list. And while they're at it, they need to figure out how much longer they can allow the Lidge adventure to go on.

Amaro said he was optimistic that Ruiz's injury would not be a long-term issue. He had better be right, because losing Ruiz for an extended period of time has been one of the team's biggest fears all season.

The Phils have blown through a lot of catching depth since December. Jason Jaramillo was traded for Ronny Paulino, who later was traded. Chris Coste was waived. Highly regarded youngster Lou Marson was traded. There isn't a catching prospect in the system above single A.

There were different reasons that each catcher was deemed expendable. But Ruiz's development as the unshakable No. 1 catcher in the organization was a common thread in the decision to part with each of them.

Amaro has said that he does not regret making any of those moves, that sometimes you have to take risks in the game. Marson is the catcher who would look best filling in for Ruiz, but he was sent to Cleveland for Cliff Lee. Lee likely will start one of the first two games of the playoffs. No one regrets or questions dealing Marson for him. But the cost of the deal is that the Phils lost their major-league-ready catching depth. You have to deal with it - while hoping for Ruiz's quick and successful return.

"We can't afford to lose anybody that plays that much," manager Charlie Manuel said.

He was right, of course. This team is not blessed with great depth. Losing Ryan Howard, Chase Utley, Jimmy Rollins, Jayson Werth, or just about any other regular for a significant amount of time could be devastating.

On the surface, it might be a stretch to equate Ruiz to Howard, Utley, Rollins and others, but this guy's importance goes beyond the box score and the stat sheet. Good catchers become the nerve centers of their teams, their value extending from behind the plate to the pitcher's mound. Ruiz, 30, has blossomed into a trusted leader for the pitching staff. He puts down the fingers, and the pitchers follow his lead.

"Our pitchers have a lot of confidence in Carlos," said pitching coach Rich Dubee, who loves the way Ruiz immerses himself in a game and treats a pitcher's performance as if it is his own.

Ruiz is a fearless blocker of balls in the dirt. He is as heads-up as they come. How about the play he made gunning down the Mets' Daniel Murphy at third in the eighth inning of a 1-0 win two Sundays ago?

Ruiz swung the bat well in the National League Championship series and World Series last year, hitting .344 (11 for 32) with four RBIs in those two rounds. Still, whatever the Phillies get from him offensively has always been considered gravy. Get out the soppin' bread, because lately there's been plenty of gravy coming out of the No. 8 spot in the batting order. Since Aug. 1, Ruiz has hit .311, with a .405 on-base percentage.

No one is saying that Bako, Ruiz's replacement last night, can't get the job done. He's a competent veteran. He's been through the wars.

But over the last year or so, the job has become Ruiz's, and he has done it well.

He is not the team's most valuable player, but there's no disputing his value.

The Phils need him to get healthy. In a hurry.

Contact staff writer Jim Salisbury at 215-854-4983 or jsalisbury@phillynews.com.