Jake Arrieta was perfect through six innings on Sunday night before accumulating his major league-best 21st win of the season, stopping Pittsburgh’s eight-game winning streak in the process.

Arrieta retired the first 18 batters he faced before Gregory Polanco grounded a leadoff single into left field in the seventh. He struck out nine while improving his record to 15-1 with a 0.89 ERA in his last 19 starts.

He even helped his own cause by hitting a home run in the second inning off A.J. Burnett.

The finish on the pitches from the side is incredible,” Cubs Manager Joe Maddon said, “meaning the carry into the catcher’s glove, the carry on the fastball, the break on the cutter-slider — whatever he wants to call it — it’s just the finish on the pitch and you can see the hitter’s reaction, it’s incredible to watch.”

Arrieta is striking out 9.2 batters per nine innings and inducing more swinging strikes that at any point in his career (11 percent). Right-handed batters, left-handed batters — it doesn’t matter. He is getting them to swing and miss all over the strike zone.

He is also showing everybody he deserves to be the National League Cy Young award winner over Dodgers ace Clayton Kershaw and his teammate Zack Greinke.

Kershaw is 15-7 with a 2.25 ERA, striking out 281 batters in 220 innings. His FIP (or fielding independent pitching) is 2.11, the best in the majors. His xFIP, calculated in the same way as FIP, except it replaces a pitcher’s home run total with an estimate of how many home runs they should have allowed given the number of flyballs they surrendered while assuming a league average home run-to-flyball percentage, is 2.17 — also the best in baseball.

Greinke has an astoundingly low ERA (1.65), which if it holds would be the lowest in a full season since Greg Maddux (1.63) in 1995.

Arrieta, meanwhile, is producing a historically low post-all-star break ERA (0.95) while continuing to set a career high in innings pitched, going past 200 for the first time in his career.

Kershaw is second to Nationals’ slugger Bryce Harper (9.7 fWAR) in wins above replacement (7.9), while Arrieta is fourth (7.1) and Greinke is 10th (5.6).

But Arrieta has been the winning pitcher for the Cubs when it has mattered the most, going 9-1 individually and 10-3 as a team when he’s on the mound after a loss, per ESPN Stats and Information.

While I would agree pitcher wins are more of a team stat than an individual stat, those that vote for the end-of-season awards feel differently. According to Tom Tangos’s simple Cy Young Tracker, which projects how the Baseball Writers’ Association of America will vote, his winning streak and ERA has now established Arrieta as the front runner.

And using end of season projections, Arrieta should finish ahead of everyone.

He’s from another planet,” catcher Miguel Montero said after the game. “There’s no doubt in my mind he’s the best right-handed pitcher in the game right now, and he showed it. He kept on showing everybody what he brings to the table every time he takes the mound — a possible no-hitter all the time.”