By Matt Spiegel–

(CBS) This can’t possibly happen that often, you say to yourself. You text your baseball loving pals, maybe you hit a website or two to dig around. It comes up over drinks.

How often is one city the home of two dominant ace pitchers on two different teams?

White Sox left-hander Chris Sale is off to one of the best starts a pitcher has ever had. He has tweaked his approach, pitching more to weak contact and varying velocity on all his pitches with hopes of going deeper into games. While his K/9 rate is the lowest of his career, this rare intentional adjustment has only increased his effectiveness.

Sale is one of only three pitchers in history to win his first nine starts while also having an ERA under 1.75. Sal Maglie of the New York Giants did so in 1952 and Eddie Cicotte of the White Sox did so in 1919.

Entering Tuesday evening’s start against the Indians, Sale is 9-0 with a 1.58 ERA. It’s hard to imagine anyone other than Sale winning it in the American League Cy Young this year, even though it’s not yet June.

Cubs right-hander Jake Arrieta has picked up almost exactly where he left off in his dominant 2015 season in which he won the Cy Young. At 1.29, his ERA is nearly a half-run better. His walks-per-nine innings is up by a full walk, but his hits-per-nine innings is down by more than a full hit.

Arrieta could easily win the Cy Young again, though Clayton Kershaw, Noah Syndergaard and Madison Bumgarner lead a deep field of NL excellence.

The divide among North and South Side fans in this town is healthy. It’s fun. It’s tradition, taught and learned. It’s a reality, and railing against it is fairly useless.

However, partisan hatred too often blinds some from appreciation of true greatness. Every week in this city offers two must-watch games. In a golden era for pitching, with so much phenomenal pure stuff in the league, don’t deny yourselves enjoyment of either of the very best.

With help from the outstanding Chris Kamka of Comcast SportsNet, let’s look at the scarcity of this confluence, through a few different prisms.

Since the Cy Young started being awarded in each league in 1967, two pitchers from the same city have never won it in the same season. In 1992, the Cubs’ Greg Maddux won the NL Cy Young, while the White Sox’s Jack McDowell finished second in AL voting. Maddux went on to win the next three in Atlanta, while McDowell won the AL Cy Young in 1993 before fading quickly.

If we envision Canada as one vast continuum, there was a Cy Young exodus in 1997 to Montreal’s Pedro Martinez and Toronto’s Roger Clemens.

Sale should be a lock for the All-Star Game starting nod from Royals manager Ned Yost. In the NL, Mets manager Terry Collins has options, the brilliant Kershaw and his own guy in Syndergaard among them. On four occasions, the All-Star Game starters have hailed from the same city, if we bend the rules to include the Bay Area.

Carl Hubbell (New York Giants) vs. Lefty Gomez (New York Yankees)

Warren Spahn (Boston Braves) vs. Mel Parnell (Boston Red Sox)

Don Drysdale (Los Angeles Dodgers) vs. Dean Chance (Los Angeles Angels)

Dave Stewart (Oakland A’s) vs. Rick Reuschel (San Francisco Giants)

The Cy Young and All-Star Game are voter-driven. In earlier times, wins were valued far more than they are now, with true dominance often unrewarded. And that’s what we should find comparisons for — two-sided excellence.

Arrieta and Sale are first and third, respectively, in ERA in the big leagues entering play Tuesday. Sale is second in WHIP (0.72), while Arrieta checks in at third (0.84). Arrieta’s eight wins trail only Sale’s nine. They’re both in the top 10 in innings pitched, signifying an ace-level workload.  Kershaw has nine quality starts. Sale is one of five pitchers tied for second with eight, while Arrieta is one of the 15 right behind him with seven.

Arrieta is eighth in FIP (Fielder Independent Pitching), while Sale is 12th. Interestingly, while Arrieta’s xFIP is also eighth, Sale’s xFIP is all the way down in 26th place, largely because of the aforementioned decrease in strikeouts. In BABIP (batting average on balls put in play), Sale is first and Arrieta is second. They’re consistently inducing weak contact.

Those are the stats I look at as I’m evaluating starters. If the BABIP seems misleading, I dig deeper, to line-drive percentage and hard-hit contact in general. I seldom go immediately to WAR (wins above replacement) when it comes to starting pitchers, instead wanting a full, nuanced picture. But for the sake of some historical research, WAR can serve as a useful shorthand.

In pitcher WAR right now (according to Baseball Reference), Kershaw is tops with a 3.6. Sale is second with 3.0, and Arrieta is third with 2.9. That feels fair.

There have been 20 seasons in which two pitchers from different teams in the same city totaled a bWAR of 7.0 or greater. But it has happened just six times since 1930.

Here they are:

Lefty Gomez, Yankees, 8.2
Carl Hubbell, Giants, 7.2

Bobby Shantz, Philadelphia A’s, 9.1
Robin Roberts, Phillies, 8.3

Dean Chance, Angels, 9.3
Don Drysdale, Dodgers, 8.0
(also Sandy Koufax at 7.4)

Wilbur Wood, White Sox, 11.7
Fergie Jenkins, Cubs, 10.3

Catfish Hunter, Yankees, 8.1
Tom Seaver, Mets, 7.8

Mark Prior, Cubs, 7.4
Esteban Loaiza, White Sox, 7.2

There are two more from Chicago, pre-1930.

Ed Walsh, White Sox, 10.1
Mordecai Brown, Cubs, 8.2

Eddie Cicotte, White Sox, 9.5
Grover C. Alexander, Cubs, 7.4
(also Hippo Vaughn at 7.3)

Now you can text that friend back or throw your knowledge around loudly between drinks. This kind of dominance just doesn’t happen often in the same city.

White Sox left-hander Jose Quintana is eighth in bWAR among pitchers, with a 2.1. He could conceivably join Sale and Arrieta, like Koufax joined Drysdale and Chance in 1964.

I agree with Score columnist Tim Baffoe, who suggests that Robin Ventura and Joe Maddon should try to give this town what we deserve on July 27 or 28: Sale vs. Arrieta in interleague play. Put aside your respective ballclub goals for consistency, gentlemen, and do it for us.

It would be the only night all season when two must-see games gets whittled down to one.

Except for late October, of course.

Matt Spiegel is a host on the Spiegel and Goff Show on 670 The Score from 9 a.m.-1 p.m. on weekdays. Follow him on Twitter @MattSpiegel670.