But on a late-spring afternoon in the twilight of a career, Rivera set down the Los Angeles Dodgers in order — flyout, strikeout, strikeout, the last against Yasiel Puig, the Cuban phenom born a few months after Rivera went pro 23 years ago. And in his three outings since, Rivera has allowed 2 of the 11 batters he has faced to reach base, resuming at age 43 his parsimonious ways, having allowed in his 19 big-league seasons one batter to reach base per inning.
Since his debut in 1995, Rivera has thrown 1,2482/3 innings and allowed a combined 1,253 walks and hits. His career WHIP — walks plus hits divided by innings pitched — is almost exactly 1.00.
How remarkable is that? Of the roughly 1,000 pitchers who have thrown at least 1,000 innings in a span going back nearly a hundred years, Rivera is the only one to keep batters off base at such a high rate. The average WHIP today, according to Elias, is 1.29, a full 29 percent higher.
Rivera’s only peers played a century ago. They are Addie Joss of Cleveland (0.97) and Ed Walsh of Chicago (1.00), the only pitchers, according to Elias, to throw at least 1,000 innings and post career WHIPs of 1.00 or less. Joss and Walsh, who retired in 1910 and 1917, played in the dead-ball era, when pitching dominated; Rivera has thrown his cutter through two decades of steroid use and often booming offenses.
Dressing at his locker recently, Rivera said that he knew none of this. He had never heard of Joss or Walsh. He had never heard of WHIP. He was mindful only of runs, not runners.
“I just attack the hitters,” he said. “I got to get three outs.”
For ages, baseball statistics were similarly simple. Pitchers were measured by little more than wins, strikeouts, earned run average and saves. Stats grew more sophisticated as sabermetrics — the use of advanced statistics whose name is derived from the Society of American Baseball Research — began to take root in the late 1970s.
In the winter of 1979, the writer and editor Daniel Okrent invented WHIP (called “innings pitched ratio” at the time) in conjunction with a game he created to enable fans to assess player performance. (The statistic did not include the small number of hit batsmen, Okrent said, for the simple reason that the Sunday papers did not include them in their weekly statistical updates.)
“I’d always felt that the number of base runners was the single greatest determinant of pitcher performance,” Okrent said. “It turned out it did correlate.”
Six of the 10 leaders in career WHIP are in the Hall of Fame, including Joss and Walsh. Among the other four are Rivera and Pedro Martinez, who are shoo-ins for the Hall, and Trevor Hoffman, who might make it, too. The closest active pitcher is the Dodgers’ Clayton Kershaw (28th, at 1.117).
“It’s essentially the pitcher’s equivalent of on-base percentage,” said Michael Fishman, the Yankees’ director of quantitative analysis, likening WHIP to O.B.P., a staple stat to measure batters.
Fishman added that WHIP offered a good “snapshot” of a pitcher, which must then be further developed by statistics not indicated by WHIP, among them the number of home runs and strikeouts a pitcher yields and records.
By just about every metric, simple or complex, Rivera is the greatest relief pitcher ever. His 634 career saves and 2.20 career E.R.A. are tops among relievers. His adjusted E.R.A.+ — a new statistic that accounts for pitchers’ abilities across different ballparks and epochs — is far and away the best in history.
And his postseason numbers are even better. In 141 postseason innings, Rivera has a laughably low 0.70 E.R.A., a WHIP of 0.76 and 42 saves.
Okrent and Fishman said that Rivera’s game nonetheless defies objective analysis.
Fishman noted that the batting average of balls hit into play against Rivera was particularly low, which normally indicated luck. But with Rivera, he said, it indicated instead that batters did not hit his pitches solidly.
“A lot of balls are easy to field,” he said. “Just watching, you see how poor the quality of contact is.”
Okrent, meantime, marveled at Rivera’s seeming one-dimensionality.
“To me, the miracle of Mariano is that he only throws one pitch,” he said of Rivera’s cut fastball. “It just doesn’t make any sense.”
As batters who have faced Rivera will say, they do not hit Rivera hard for the same reason he has dominated them with but one pitch: that pitch is uniquely good, with late movement that has broken an enormous number of their bats.
If others attribute Rivera’s success to his cutter, Rivera attributes his cutter to Christ. Stitched into his glove is “Phil. 4:13,” the verse in the biblical book of Philippians that reads, “I can do all things through Christ who strengthens me.”
Asked at his locker about the Bible, Rivera said that of all its characters, King David “is the person I can relate to.”
“He was a king,” Rivera said. “But he knew what his source was: the Lord. And he was a humble man.”
That the young David saved a people with his arm, hurling a stone, Rivera did not mention. As a boy he also threw stones, winging them on the Panamanian shore where his father fished for sardines and shrimp. Asked of David’s slingshot, Rivera insisted with a smile that it was entirely beside the point.
Rivera is kinglike. He has reigned for 19 years, and his teammates hold him in commensurate awe. Outfielder Vernon Wells can still describe in detail the Rivera pitch he hit for a home run to end a game while with the Toronto Blue Jays in 2006.
Catcher Chris Stewart still has the ball he asked Rivera to autograph for him in 2007, when he was a Texas Ranger. And even pitcher Andy Pettitte, a winner of 250 big-league games (71 saved by Rivera), marvels at his teammate.
“His mechanics are perfect,” Pettitte said. “And he only throws one pitch.”
Unlike Rivera, Pettitte said he was mindful of WHIP. (His career WHIP is 1.35.) He said that Rivera’s WHIP was so low because of his unequaled ability “to command the zone.” By this he means that Rivera can always throw a pitch where and how he wants.
For this reason, Rivera is as easy to catch as he is hard to hit.
“You know where it’s coming,” said Jose Molina, a veteran catcher who caught Rivera over three seasons, from 2007-9. “He’s going to hit his spot.”
That spot, Stewart added, is “usually in to the lefties, away from the righties.”
Everybody knows this — Rivera, the catcher, the umpire, the batter, the fielders, too. And so, when Rivera takes the mound, there is an inevitability about what will happen that is largely absent in sports.
“Most lefties are going to end up getting around,” Wells said. “Most righties, you can play them true” — that is, straightaway. “His cutter is going away from them.”
Second baseman Robinson Cano added: “You don’t have to worry that anyone is going to hit a bullet. He breaks more bats than any other pitcher.” And so, Cano said, it is as easy to field behind Rivera as it is to catch him.
Because Rivera retires nearly every batter he faces, he can pitch over and again. This is the greatest benefit of his low WHIP.
“It’s quick innings,” Larry Rothschild, the Yankees’ pitching coach, said.
Reliever Dave Robertson, who often pitches just before Rivera, added, “It means he’s available tomorrow.”
Rivera has few tomorrows left on the field. But on the last day of spring in his last season, he seemed only happy, singing a Spanish song as he sat at his locker in his uniform, preparing to do what he has done better than any other pitcher for 100 years: prevent batters from advancing the 90 feet from home plate to first base.
Rivera may not pay such relative minutiae any mind, may not know that he has allowed a combined four more walks and hits than the number of innings he has pitched.
But he knows well that he has played for one team at one position throwing above all one pitch for one inning at a time. And were Rivera at the end of his career to average no more than one batter to reach base each of those innings — were he to finish with a WHIP of 1.00 — it would be the perfect encapsulation of a career that can best be defined by that same number.
“That’s me,” Rivera said with a smile. “I like to simplify stuff.”