We know it's recently been a bit of a rough patch for the Cubs' rotation. Over the past 30 days, John Lackey has a 5.14 ERA, and we point that out because it's the lowest among the quartet of himself, Jake Arrieta (6.14), Jon Lester (7.23) and Jason Hammel (5.88). Obviously, a great deal of attention has been focused on that issue, as well as trades for relievers Aroldis Chapman and Mike Montgomery. Too much attention, perhaps. Have you noticed that while the rest of Chicago's rotation has been falling apart, Kyle Hendricks has been absolutely untouchable?
It's not hyperbole, because it's true. Hendricks hasn't allowed an earned run in three July starts and a two-inning relief appearance, and he's allowed more than two earned runs just once in his past 11 starts, giving up three to Washington on June 13. On the season, he's got baseball's third-lowest ERA (2.27), behind Clayton Kershaw and Madison Bumgarner, ahead of Noah Syndergaard and Johnny Cueto.
If Hendricks gets through 5 1/3 innings in tonight's start against the White Sox without an earned run, he'd set a record, because no one has ever thrown at least 25 innings in July without allowing one earned run for the month. He'd be just the 11th pitcher to do that in any month, and eight of those came before the divisional play era began in 1969. No one's done it since Orel Hershiser, who did it in the midst of his record-setting streak of 59 shutout innings in 1988. 

This is the same Hendricks who had to fend off Adam Warren and others to retain the fifth starter job in the spring. It's the same Hendricks who averages just 88 mph on his primary sinking fastball. How is he doing this? And can that soft-tossing profile really be trusted in October, when every bad batted-ball bounce looms large?
Here's how Hendricks is succeeding:
He's a master of getting the right kind of contact.
If you're not piling up strikeouts, you'd better be doing something else at a high level, namely preventing hard contact. Last year's leaders at allowing the lowest exit velocity were Arrieta, Kershaw and Dallas Keuchel, which tells us that doing so may be a skill, and as you'd expect, this is a big part of how Hendricks succeeds. Of the 124 pitchers with at least 200 batted balls allowed, Hendricks' 87.1-mph velocity against is tied with Kershaw for seventh.
We can dig deeper than that. Thanks to that sinker, Hendricks collects an above-average number of grounders: 52 percent. The Major League average is 45 percent. Grounders don't usually turn into extra-base hits, so already Hendricks is setting himself up to prevent damage. And when he does allow a ball in the air, at a launch angle between 20 and 50 degrees that includes nearly all line drives and fly balls, he doesn't let it get hit hard. One hundred fifty pitchers have allowed 50 such batted balls, and only one, Scott Feldman, has allowed a lower exit velocity than Hendricks' 85.7 mph.
How important is that? The Majors hit .337 on balls between 20 and 50 degrees. Ninety-four percent of all home runs come between 20 and 50 degrees. That's the danger zone, and Hendricks limits the damage.
Gif: Hendricks and Maddon bump fists
He gets a ton of called strikes, because he masks his pitches well.
As you might expect, a pitcher with Hendricks' profile isn't blowing the ball past hitters, though he does get more swinging strikes than you'd think -- his swinging-strike percentage of 9.2 percent is 54th among 93 qualified starters, essentially tied with Chris Tillman, Cueto and Jeff Samardzija. That's mostly thanks to Hendricks' elite changeup, which gets more swings per pitch than any pitcher other than Danny Salazar and David Price, and a top-10 swing-and-miss rate.
But Hendricks has also become elite at getting called strikes, because despite the relative lack of velocity, hitters have a difficult time discerning his pitches. Very elite, actually. There have been 333 pitchers who have thrown 500 pitches this year, and only one -- Aaron Nola -- has a higher called-strike percentage than Hendricks. Last year, if you increase it to 1,000 pitches, he was fourth of 260. How? In part because he releases all of his pitches from the exact same release point, giving the hitter nothing to pick up on:

The Cubs have a very good defense.
It goes without saying that run prevention is a team effort. Obviously, the pitcher plays a big role by limiting walks and hard contact, but if the ball is in play, the defense needs to turn it into outs. If you go by Defensive Runs Saved, the Cubs are No. 1. If you go by Ultimate Zone Rating, the Cubs are No. 1. If you prefer the simpler Defensive Efficiency, which just asks, "How often does a ball in play turn into an out?" the Cubs are No. 1.
But we can also use Statcast™ to show that the Cubs are improved this year, particularly since they shifted pieces around in their outfield. -- Dexter Fowler remained in center, but Jason Heyward took over in right, there's been a lot less Kyle Schwarber and Jorge Soler in the corners, and they've strategically played deeper.
If we look at non-home run, non-grounder batted balls between 200 feet and 400 feet (i.e., balls that the outfield should have some chance of converting into an out), the Cubs rank No. 1 there, too, allowing a Major League-best .356 average against. The next two teams are Atlanta, which has Mallex Smith and Ender Inciarte, and Kansas City, well-known for stellar outfield play. Overall, Major League teams allow a .409 average against on those balls, more than 50 points higher than the Cubs do.
Last year, the Cubs were fourth from the bottom in allowing a .418 average against. It's a pretty enormous difference. Hendricks is successful because he's a good, solid, underrated pitcher. He's also playing in front of what looks like baseball's best and most-improved defense. When Hendricks is not piling up called strikes or grounders, he's getting softly hit fly balls to a good outfield defense. It's a nice spot to be in.