NEW YORK -- The season of the incredible disappearing closer took another twist this weekend with the disabling of Yankees great Mariano Rivera and San Diego's Huston Street, not to mention Heath Bell losing his role for the time being in Miami.

Nine elite closers currently are on the disabled list, including the stoppers from four of the five teams in the American League East. Brian Wilson of the Giants, Joaquin Soria of the Royals and Ryan Madson of the Reds are all down after Tommy John ligament replacement surgery, and won't be back until well into next year.

In addition, three other closers aside from Bell have already been displaced, and Detroit's Jose Valverde has been struggling, although he recorded his fifth save on Sunday.

"It's a very intense job, both physically and mentally," said D-backs manager Kirk Gibson before the Mets handed his club a 3-1 defeat at Citi Field on Sunday. "Every time they're in, they have to go all out. They go hard. The injuries are an occupational hazard."

In this day and age of the specialty reliever, most closers throw in the neighborhood of 70-80 innings a year. Gibson has to watch the load he puts on his own J.J. Putz, who threw only 58 innings last year and spent a stint on the DL with right shoulder tendinitis. He still saved 45 games.

Putz, though, has a history of arm trouble, and only saved five games for the Mets and White Sox between 2009 and 2010.

"We try to do as much as we can to take the pressure off him," Gibson said. "We have David [Hernandez], who can close a game. We have [Bryan] Shaw, who can close a game. You just have to really stay on top of it, certainly early on. When it gets down to the end, though, you've got to go."

It wasn't always that way. Back in the era when Gibson played, closers routinely racked up more than 100 innings a year, and rarely were hurt. Rollie Fingers, Rich Gossage and Bruce Sutter were all multiple-inning closers and Hall of Famers. Only Sutter's career ended early, because of a shoulder injury.

When Gibson's Tigers defeated Gossage's Padres in the 1984 World Series, both closers were workhorses. Gossage pitched 102 1/3 innings and saved 25 games that season. Willie Hernandez threw a whopping 140 1/3 innings for the Tigers, saving 32 games and winning nine more. He was named both the Cy Young Award winner and MVP of the American League.

On the other two teams that lost in the playoffs that year, Dan Quisenberry threw 129 1/3 innings and saved 44 games for the Royals, and Lee Smith tossed 101 innings and saved 33 games for the Cubs.

What changed? Even when then A's manager Tony La Russa broke new ground and went to the multi reliever format in the late 1980s, using Dennis Eckersley for the ninth inning only as a closer, the Hall of Fame right-hander had a lot of miles on his arm already as a starter. And he never was hurt.

"I think it's different now, I really do," Gibson said. "Today, overall, guys are bigger, stronger. They throw with more velocity, which means more deceleration. It used to be fastball, slider. Now it's more cutters. There's no answer for it. You just do the best you can."

But that doesn't really explain the unimaginable spate of injuries and the general lack of effectiveness of many closers. Going into Sunday's game, Major League relievers had already blown 115 saves with the season barely 30 games old for most teams.

It may simply all come down to better conditioning.

"It's a rock-star position," said D-backs TV play-by-play man Daren Sutton, whose father, Don, won 324 games for five teams and is in the Hall of Fame. "If you want to be a rock star, you have to stay in shape. That's what I notice."

For more than a decade, fans have been used to watching the consistency of Rivera and Trevor Hoffman. Other than their amazing success, the common thread between the two closers is their work ethic and dedication to staying in shape.

Hoffman retired after the 2010 season with 601 saves, and he excelled in his workout regimen to the very end. When Rivera tore an anterior cruciate ligament in his right knee shagging a fly ball in batting practice this past Thursday, he was secure in the all-time lead with 608. It's a mark that no reliever may ever reach again, because the job has become so taxing.

"If I had an answer to all that, I'd be in a bigger position than I'm in," said Mets manager Terry Collins, whose own closer, Frank Francisco, recorded his seventh save of the season to close out the D-backs on Sunday. "There are so many pitchers being injured today, more than there was years ago. This is being investigated on a yearly basis by the strength and conditioning staffs and the trainers.

"The only thing I can tell you is that these guys are a lot bigger and a lot stronger than 30 years ago. It's got to be that these bigger muscles are just tearing up those smaller muscle groups."

Theories may abound, but one thing is for certain: As the season of the incredible disappearing closer goes on, that pattern deserves further watching and analysis.