Based on his career body of work, Dodgers left-hander Clayton Kershaw is, by consensus, baseball's top pitcher. But in looking at 2015 alone, is he the best on his own team?

Said title must be given to Zack Greinke, the starter on the National League's All-Star squad.

Video: Greinke on earning starting nod for National League

With one American League Cy Young Award already under his belt (Royals, 2009), Greinke is in the midst of his strongest campaign to date. He entered the Midsummer Classic with an 8-2 record and a 1.39 ERA that leads all pitchers by 0.65 runs (second is Sonny Gray, 2.04).

Such a low figure may conjure up thoughts of Bob Gibson's superlative 1968 campaign, when the Cardinals legend posted a minuscule 1.12 ERA. Granted, Gibson's performance did come in the "Year of the Pitcher," arguably the most depressed offensive environment (3.42 runs per game) since the dead ball era. By comparison, Greinke is excelling in a year when teams are scoring 4.10 runs per contest.

But since comparing a half season to a full slate has its flaws, let's look at how Greinke's first half stacks up against historical first halves.

Best First-Half ERA since Expansion (1961) min. 12 starts Player Year First-Half ERA Eventual ERA Bob Gibson 1968 1.06 1.12 Luis Tiant 1968 1.24 1.60 Don Drysdale 1968 1.37 2.15 Zack Greinke 2015 1.39 ??? Vida Blue 1971 1.42 1.82

Greinke has the lowest first-half ERA since 1968, when Don Drysdale (1.37), Luis Tiant (1.24) and Gibson (1.06), all had marks below that of the active Dodgers righty. However, Greinke's 0.84 WHIP leads the group, which posted marks ranging from 0.85 to 0.93.

Unsurprisingly, none of the aforementioned retirees sustained their first-half ERAs, finishing with figures that averaged 0.4 runs above their first-half marks. If Greinke were to follow suit, he would end 2015 with a 1.79 ERA -- a hair above Kershaw's 1.77 from last year.

If Greinke pitches to his current 2.65 FIP for the rest of the season, his overall ERA would fall just below 2.00. Such a performance would put him in historic company as just the sixth different qualified starter since 1994 with a sub-2.00 mark.

Given his work this year and during his AL Cy Young Award-winning campaign, is Greinke worth being considered a great of his generation? Let's take a look.

The 2009 version of Greinke posted one of the best pitching seasons in memory. He put up the game's highest single-season pitcher WAR (10.4) since 2003.

Compared to all player-seasons in that span, the effort ranks third overall behind Barry Bonds in 2004 (10.6) and Mike Trout in '12 (10.8).

Best pitching seasons, 2003 to present Player Year WAR Zack Greinke 2009 10.4 Roy Halladay 2011 8.9 Cliff Lee 2011 8.6 Johan Santana 2004 8.6 Randy Johnson 2004 8.5

For those who view Greinke as one of this era's top arms, I have another question for you: Should Greinke be on the Hall of Fame's radar?

I think so. After all, Greinke has gone 40-14 with a 2.36 ERA and a 1.06 WHIP since moving to Chavez Ravine prior to the 2013 campaign.

Want more evidence? During the course of his career, Greinke has averaged 4.49 WAR-per-200-innings. That's rare, folks. In fact, only 19 starters in history have composed such a pace over the entirety of their baseball careers, and six of the seven that retired before 2000 are enshrined in Cooperstown. Noodles Hahn, who last played in 1906, represents the lone exception.

Active WAR leaders among pitchers Player Age WAR Mark Buehrle 36 59.7 Tim Hudson 39 57.9 CC Sabathia 34 54.8 Felix Hernandez 29 48.9 Zack Greinke 31 47.4 Cliff Lee 36 44.3 Cole Hamels 31 44.2 Bartolo Colon 42 43.7 Clayton Kershaw 27 43.5 Justin Verlander 32 41.3

Although victory totals have been rejected by the sabermetrics crowd, wins still have a bearing in the minds of many Hall of Fame voters. In that department, Greinke is tied for fifth among hurlers since 2009 (97), and ranks first in winning percentage (.674) among those with at least 50 decisions.

If he's been so good, why doesn't Greinke get more credit as a possible Hall of Fame candidate? Overall visibility -- or lack thereof -- could be a factor.

When Greinke won his AL Cy Young Award with Kansas City in 2009, the Royals were still mired in a decades-long funk. That year, they went 65-97. And despite his quality results for the Brewers and Angels from 2011-12, he was not an irrefutable ace with either franchise.

Today -- even with his excellence in Dodger blue -- Greinke gets overshadowed by Kershaw, who is a three-time NL Cy Young Award winner and the reigning NL MVP Award winner.

Video: 7/9/15 MLB.com FastCast: Greinke dominates Phillies

Now that we have looked back at Greinke's accomplishments, let's peek ahead at what the future might bring.

Dan Szymborski, the creator of the popular and reliable ZiPS projection system, estimates that Greinke will go 89-59 with a 3.18 ERA and a 25.4 WAR from 2016 through his career's end.

Tack that 25.4 WAR onto Greinke's current tally, and you get 72.8 WAR -- a figure that would nearly make Greinke a no-doubt Hall of Famer.

Just 30 pitchers in history have posted a WAR north of 70 overall, and 26 have made it to Cooperstown (or are set to be inducted this summer). Roger Clemens, Curt Schilling, Mike Mussina and 1880s star Jim McCormick are the only exceptions.

If those late career projections seem a little too rosy, think hard about Greinke's skillset, and how he would age on the mound. As one of baseball's most cerebral minds, Greinke is bound to adjust as he grows older.

We are at least a decade away from firmly deciding on Greinke's place in baseball immortality, but that's no reason to avoid the dialogue.

However, those who wish to wait on the debate should at least enjoy Greinke's present-day performance. It's extremely special, and we may not see another half-season quite like it in some time.