By Cliff Corcoran

"Best Pitcher in Baseball" is not an official honorific. Still, it is a title that gets bandied about quite a bit. Clayton Kershaw has been the consensus Best Pitcher in Baseball for several years now and was described as such with regularity throughout the just-completed postseason. However, that consensus is starting to fragment in favor of the Nationals' Max Scherzer, who could win his second consecutive National League Cy Young Award on Wednesday. Roy Halladay, who died in a private plane crash on Tuesday, was certainly the Best Pitcher in Baseball for a portion of his career.

Given that we are in the midst of baseball's awards season, I wanted to find a way to make the title of Best Pitcher in Baseball less nebulous by putting some hard numbers behind it. Doing so would give us an objective basis to determine if Scherzer has indeed caught Kershaw, exactly when Halladay held the title, fill in the blanks in between then and now and trace some of the legacy of the title.

The trick to determining the Best Pitcher in Baseball is that the title is indicative of sustained dominance. As the Kershaw/Scherzer debate indicates, Best Pitcher in Baseball is not a title that changes hands regularly or easily. A single great season by a challenger is rarely enough to dethrone the Best Pitcher in Baseball, and the Best Pitcher in Baseball needn't to win -- or even deserve -- the Cy Young Award every year to retain the title. However, he must perform at an elite level over multiple seasons. I've often said that the mark of true greatness is when something or someone lives up to the highest possible expectations. The Best Pitcher in Baseball does that year-in and year-out.

As a result, determining the Best Pitcher in Baseball statistically requires a multi-year sample. A rolling average would do the trick up to a point, but because I do want to determine who held the title on a season-to-season basis, some weighting of those seasons would be preferable.

Almost 10 years ago, Nate Silver, then at Baseball Prospectus, had similar questions about the title of Best Player in Baseball, which was then a close competition between Albert Pujols and Alex Rodriguez. To answer them, he devised a weighting scheme that looked at rolling, six-year samples of a player's career, including the three years prior to the season in question and the two years after. Because these honorifics are based on reputation, Silver put more weight on the previous seasons, with the season in question counting for 31 percent of the score, the previous three seasons counting for a total of 42 percent and the two subsequent seasons counting for a mere 17 percent, just enough to protect against a spike in performance. The overall scheme looked like this:

7 percent: Year N-3
13 percent: Year N-2
22 percent: Year N-1
31 percent: Year N
18 percent: Year N+1
9 percent: Year N+2

Running Baseball-Reference's wins above replacement totals for the best pitchers of the past 55 years through Silver's scheme, I was very satisfied with the results. As someone who has been a passionate baseball fan for more than 30 years and has covered the sport for nearly 15, I've long had a roughly sketched mental list of the Best Pitchers in Baseball in my head. The results from this process largely matched that less scientific accounting.

First things first: Kershaw no longer holds the title. Kershaw vs. Scherzer was a popular topic of debate this summer. I argued in Scherzer's favor on a mid-June appearance on "MLB Now," citing as possible signs of decline Kershaw's spike in home runs allowed, the decline in his strikeout-to-walk ratio and, most importantly, his struggle to avoid the disabled list, something he has failed to do in three of the last four seasons. What the numbers tell us here, however, is that we were all late to the party. Scherzer passed Kershaw last year, and Kershaw's fragility is the primary reason why.

On an inning-by-inning basis, Kershaw out-pitched Scherzer both last year and this. However, Scherzer has thrown 105 more regular-season innings than Kershaw over the past two seasons, has struck out 178 more batters and has been worth 3.3 more wins above replacement, per bWAR. By way of comparison, Kershaw's All-Star rotation-mate, Alex Wood, was worth 3.3 bWAR this season and struck out 151 batters. As it turns out, the gap between Scherzer and Kershaw is large enough that Corey Kluber, who could win his second AL Cy Young Award on Wednesday, has also surpassed Kershaw and is neck-and-neck with Scherzer with scores of 4.95 and 4.97, respectively.

Kershaw did hold the title for four years, from 2012-15. Since 1962, only one pitcher has held on to the designation for longer. That was the young Roger Clemens, who was the Best Pitcher in Baseball from his breakout season in 1986 all the way through his age-29 season in 1992. Over that seven-year span, Clemens posted a 2.66 ERA (160 ERA+) and 1.09 WHIP and averaged 239 strikeouts in 257 innings per season. He won three American League Cy Young Awards, with two other top-three finishes, and the 1986 AL MVP Award.

Four other pitchers since 1962 have held the title for four consecutive years, and one other held if for four non-consecutive years. Bob Gibson was the Best Pitcher in Baseball from 1967-70. Knuckleballer Phil Niekro held the title from 1976-79, a stretch during which he averaged 42 starts, 319 innings, 19 complete games and 8.3 bWAR per season. Greg Maddux held the title from 1994-97. Mad Dog was succeeded by Pedro Martinez, who was the Best Pitcher in Baseball, and maybe ever, from 1998 to 2000. Pedro passed it to Randy Johnson for two years, took it back in 2003, then returned it to the Big Unit in 2004. From 2005-08, the best pitcher in baseball was Johan Santana.

Santana's dominance intruded upon Halladay's. From 2004-08 (yes, I added an extra year at the beginning there), Santana posted a 2.82 ERA (157 ERA+), 1.02 WHIP, an average of 238 strikeouts in 229 innings and 7.1 bWAR per season. He also won two AL Cy Young Awards, deserved at least one more and led his league three times each in ERA, ERA+, strikeouts, strikeouts per nine innings and FIP, plus WHIP four times and innings twice.

Halladay had his first great seasons while Martinez was still dominating the American League, winning his first AL Cy Young Award in 2003. He then suffered a pair of injury-shortened seasons, which undermined the head-start he got on Santana. Halladay's greatest period of dominance began in 2008, when he finished second in the AL Cy Young Award voting to Cliff Lee's breakout season. Halladay also finished a very close second to Santana in the Best Pitcher in Baseball scoring for 2008, 5.79 to 5.76, a virtual tie given the vagaries of WAR.

In 2009 and '10, Halladay was the Best Pitcher in Baseball. He was every bit as good in 2011; however Justin Verlander's AL MVP Award campaign gave the Tigers ace a one-year cameo as the Best Pitcher in Baseball (6.23 to Halladay's 5.99). By 2012, Halladay's arm and back had started to give out, and Kershaw ascended to the title.

Two years as the Best Pitcher in Baseball may fall short of your memories of Halladay, but consider this list of the pitchers who have held the title for multiple years since 1962: Sandy Koufax (1963-65), Gibson, Tom Seaver (1971, '73 and '75), Niekro, Steve Carlton (1980-81), Dave Stieb (1982-84), Clemens, Maddux, Martinez, Johnson, Santana, Halladay, Kershaw and Scherzer. There are no flukes there, no flashes in the pan. Stieb is the least celebrated of those pitchers, but he held the title for three years, the start of a four-year stretch in which he posted a 148 ERA+ while averaging 275 innings and 7.3 bWAR per season. There's a case to be made for Stieb as an Eras Committee Hall of Fame inductee (though he was left off this year's Modern Baseball ballot). Of the 10 men on that list who are eligible for the Hall of Fame, all but Stieb and Clemens are in, and the argument could be made that the rest should get there in time (though Scherzer is still building his case). Meanwhile, half of the pitchers on that list are likely to come up in a conversation about the greatest pitcher in Major League history.

The one-offs who filled in the gaps were an impressive group, as well. They were Don Drysdale in 1962, Juan Marichal in '66, workhorse knuckleballer Wilbur Wood in '72 (49 starts and 376 2/3 innings!), Gaylord Perry in '74 (7.55 to 7.51 over Seaver in an off-year for the Franchise), Dwight Gooden in '85 (one of the greatest pitching seasons in Major League history), Kevin Appier (perhaps the most underrated pitcher of the past 50 years) in '93 and Verlander in 2011. That's three Hall of Famers, with Verlander seemingly on his way.

In fact, Verlander was closer to Kershaw's score this year (3.96 go 4.16) than Kershaw was to Scherzer's 4.97. Given Verlander's strong finish with the Astros, by this time next year, Kershaw could be the fourth-best pitcher in baseball."

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Cliff Corcoran is a Sports on Earth contributor and a regular guest analyst on MLB Network. An editor or contributor to 13 books about baseball, including seven Baseball Prospectus annuals, he spent the last 10 seasons covering baseball for and has also written for USA Today and SB Nation, among others.