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07/16/06 4:27 PM ET

Longevity separates Rivera from pack

Endless production puts unshakable closer with history's elite

1993 ... 1999 ... 2005 ... 2006.

The timeline of 400th saves, Lee Smith through Mariano Rivera, doesn't suggest that we're on the brink of hordes of closers about to burst through the doors of this most exclusive fraternity.

Some current firemen could get there. Veterans Billy Wagner and Armando Benitez, and youngsters Francisco Rodriguez and Huston Street, conform to the advanced prerequisites for this magic number.

Yet, it is possible that we may not see it again. Or we may see it repeatedly from guys still in their bullpen diapers.

This is merely one of the conflicts spawned by baseball's bullpen era, in which the save has been cheapened, but crunching big numbers has become a physical and medical challenge.

Closers have been both empowered and victimized by their importance. They are the modern game's most indispensable element -- yet also the most dispensable. Bullpens should have revolving doors, not gates. That's where most teams are most in flux. Closers have shorter leashes than Chihuahua pups.

So durability and survival -- two elements virtually impossible to foresee -- are keys to immortality in this field.

Not big hauls. The ledger is full of flashes in the 'pen. Bobby Thigpen had 57 saves in 1990 and barely broke 200.

Not even hot reigns. Bryan Harvey put up 154 in a five-year run (1989-93); he didn't even make it to 200. The same jury of pain, of course, remains out on Eric Gagne, who had 152 saves in three seasons and has nine in the two seasons since.

Certainly not postseason fire. Mitch Williams notched 157 saves in a five-year span, then Joe Carter happened. Donnie Moore was rolling with 52 saves in back-to-back seasons, then Dave Henderson tragically happened.

The ability to maintain, through minor injuries and major shocks, lifts the Riveras above the crowd. In the four seasons prior to Luis Gonzalez, Rivera had 167 saves. In the four seasons after giving up the hit that lost the 2001 World Series, he had 164 saves.

That's the definition of wearing blinders to all of the job's pitfalls.

The 400 Quartet has obviously had legs, not only arms. It has had longevity and relief exclusivity in common.

Rivera has gone 10 years between his first save and his most recent. Mo also started only 10, all during his 1995 rookie season, of his 700-plus career appearances.

Lee Smith went 16 years between first and last saves, and he started only six of his 1,016 career games.

John Franco went 19 years between his first and last saves, and he relieved in each of his 1,119 games.

Trevor Hoffman is still going strong 13 years after his first save, and he hasn't started any of his nearly 800 games.

In sum, these four leading closers had a trifling 16 starts among 3,700 appearances. They were groomed for the role -- a significant element that eliminates such current hot closers as Jason Isringhausen, who spent his first 3 1/2 seasons trying to break into the Mets rotation, and even a healthy Gagne, who made 48 starts for the Dodgers before he ever heard the bullpen phone ring.

Conversely, Benitez is a hot prospect for the 400 Club. Surprising, three years after his exile from Flushing? Consider that he is actually two months younger than Isringhausen, and he has been exclusively a reliever throughout a 700-game career.

However, the 33-year-old Benitez, with 269 saves as we approach the end of June, has to overcome the injury bug that has had him on the Giants' disabled list most of this season.

Wagner, fresh into the 300 Club, is two years older than Benitez, but he obviously also has a shorter road to the 400 line. And being left-handed virtually gives him a license to keep pitching as long as he wishes -- and remains up for the physical and mental challenge.

Wagner, likewise, has exclusively relieved in 620-plus appearances across 12 seasons.

Rodriguez, 24, and Street, 22, have both prepared for this role since before signing their first professional contracts. Their current numbers -- 77 and 41, respectively, as of June 26 -- are not as significant as the consistency and resilience they have already demonstrated in a role that has worn down a countless number of their elders.

Then there are the wild cards, like Jonathan Papelbon. The Boston flash has neither the breeding nor the track record to merit even a mention in a projection of 400. But the onetime starting blue chip says that he digs the job and would like to keep at it.

So Papelbon could be the next Mighty Mo. Or he could be another in a long line of John Rockers.

Tom Singer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.