By Marc Normandin

Yankees manager Joe Girardi didn't know who his closer was earlier this week. David Robertson would have been the choice -- and was to begin the season -- but a groin injury pushed him to the disabled list, taking away the obvious answer. This is a new situation for the Yankees, but it's one they're going to have to learn to deal with now that Mariano Rivera has retired, just like every other team has learned to live without their own Rivera for the last couple of decades.

There have been other elite closers, but they have been, with few exceptions, known to be temporary solutions. It might be a year, it might be two, it might be six if you're lucky, but eventually, an elite closer breaks down, loses his stuff or signs elsewhere for massive money. Sometimes that can be a good thing: Ask the Phillies how happy they are Ryan Madson ended up signing elsewhere after 2011, instead of inking a long-term, lucrative deal with the team he had just been closing for. Sometimes it can be a terrible thing, though, depending on which side of a contract you're on: Ask the Phillies how unhappy they are they replaced Madson with the declining Jonathan Papelbon on a $50 million deal with an option, a pact that now seems immovable. The Yankees have not had to deal with any such situation in decades, thanks to the now-retired Mariano Rivera. They haven't had to go shopping for closers or try to develop one, and the one time they did sign a fireman, he was meant to be extra depth behind Rivera simply because New York could afford it.

In fact, Rivera himself was the successor to John Wetteland, a high-quality stopper who had his own elite work who led the American League in saves in his final season with the Yankees in 1996. Rivera's 1996 success as the setup man kept the Yankees from having to go spending for a closer from the start. Rivera stepped into the role in Wetteland's place in 1997and didn't skip a beat until 2012, when he missed almost the entire season due to a knee injury that required surgery.

Other than 2012, when he missed 137 games recovering from surgery, Rivera missed just 153 games from 1997 through 2013 due to stints on the disabled list -- all of the 15-day variety -- and the occasional day-to-day hurt. That's just about 10 games missed per season, or only about six percent of the total games the Yankees played in during that time frame. Rivera was not only elite on the mound, but his health was fantastic, and only once did the Yankees have to scramble to replace him for a significant amount of time due to injury. That by itself is irregular and was an advantage the Yankees could lean on in all but one season of a 17-year stretch in which they won four World Series titles.

The only other Yankee pitcher from 1997 through 2013 with more than 16 saves total is Rafael Soriano, who was the closer in Rivera's absence in 2012 and racked up 42 of his 44 pinstriped saves that year. After that, it's Ramiro Mendoza with 16, Mike Stanton with 15, Steve Karsay with 12 and Robertson with 10. When you consider Soriano, a successful closer in his own right, was around in 2012 to take Rivera's place, it becomes clear the Yankees didn't even have to learn to live without him the one time he was gone. No one is Rivera, but the elite can fake it for a season at a time.

As said, Rivera's health is just one part of it. We're talking about a pitcher who is the all-time leader in saves for a reason, and not because he just happened to be around for a long time to get to that point. Rivera's 205 ERA+ is tops among pitchers with at least 1,200 career innings. He ranks first in wins above replacement for all Yankees pitchers from 1995 through 2013, and is ninth on that list among all pitchers in that span. Being healthy is a significant reason for that, but so is being flat-out amazing at his job -- better than anyone else ever, even.

So, no pressure, Yankees, trying to replace that. Now they're stuck doing what everyone else does, trying to get by with mere mortals on the mound, pitchers who are excellent, but aren't Mo. They've already had to scramble now that their first option, Robertson, is on the disabled list, and that's because there is no Rafael Soriano to fill in the blanks this time. Shawn Kelley was Girardi's backup option when Robertson went down, the same Shawn Kelley who has been pretty hit-or-miss in his five-year career, with 2013 belonging in the "miss" bucket thanks to almost four walks per nine and eight homers in 53 innings. Maybe they'll get lucky with younger relievers like Adam Warren or Dellin Betances getting a shot and doing something with it in the role, but relying on luck is not something Yankees bullpens are used to doing.

If you're a fan of another team, you might be wondering what the big deal is. Non-Yankees teams have to put up with this kind of thing constantly, as they never had to adapt to life without Rivera. Every season has already been life without Rivera for them. The Yankees haven't done so yet because they're new at this, and it showed a little with their offseason, since they didn't bring in anyone to replace Rivera. That's not to say there was another Rivera out there -- as a 43-year-old heading toward retirement, he did post a 192 ERA+ while picking up 44 saves in 64 games, and that's not exactly easy to find -- but they could have spent some of that off-season cash on someone besides 37-year-old now-LOOGY Matt Thornton in order to shore up the Rivera-less pen more than they did.

The Yankees spent their money elsewhere, though, filling in holes in the outfield and behind the plate, likely in the hopes that the talented Robertson would do until there was an opportunity to upgrade. Now that Robertson's hurt, the Yankees are stuck with little in the way of bullpen help, and with a rotation that has question marks thanks to the early (but continued from 2013) struggles of CC Sabathia, everyone's unfamiliarity with Japanese import Masahiro Tanaka and the health of Michael Pineda. They're still a better team than they were last year thanks to the upgrades they did make, but the bullpen could easily be a problem area that keeps them from the top of a talented and competitive American League playoff picture.

It's early yet, of course, and Robertson isn't going to be out forever with a groin pull. Even Rivera pulled his groin despite his general sterling bill of health. Normally there was someone capable to fill in during those times, though. The Yankees can always make a trade if the young arms (and old ones) in their pen don't work out behind Robertson, or they can smarten up next winter and spend some of that Derek Jeter money on relief help so that Robertson isn't stuck trying to carry the load by himself. It might sound weird to have to explain all of this to a fan who is used to closer turnover, but while it's normal life in baseball for 29 other teams, it's a brand new reality for the Yankees and their fans, one they'll get used to in a hurry if they haven't already realized what life after Mariano Rivera entails.

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Marc Normandin writes and edits for Over the Monster, a Boston Red Sox blog, as well as SB Nation's baseball hub. He's one of many behind the e-book "The Hall of Nearly Great," and has written for BaseballProspectus, ESPN, and others. You can follow him on Twitter at @Marc_Normandin