Michael Lewis's Moneyball, in theory, blew up walks as an undervalued baseball skill more than a decade ago. It was a best-seller; its title is now a familiar term; and insofar as it had a thesis, it was that baseball teams can succeed by recognizing undervalued skills, and Lewis's book focused heavily on the skill of getting on base by any means, even if it meant the unsexy free pass.

But a lot of teams remained bad at it. One of those teams was the Cubs. And for all the excitement about Kris Bryant's spectacular power, Jon Lester's tremendous resume, and Joe Maddon's winning interpersonal skills, perhaps the Cubs' greatest improvement has been a newfound willingness to take a walk—and picking up extra bases thereafter.

Here's how the Cubs have fared over the past five years.

In five years, the Cubs have gone from one of the worst teams at taking a walk, to mediocre, to second-best so far this season.

A lot of this can be attributed to Kris Bryant; perhaps as a result of his insane spring, pitchers aren't pitching to Bryant, and he's not swinging. Bryant's 18.0 walk rate is fifth-highest in baseball, and he's in good company: Bryce Harper, Joc Pederson, Carlos Santana, and Jose Bautista are the only players ahead of him. As a result, Bryant's .421 on-base percentage is seventh-highest in baseball, behind Harper, Anthony Rizzo, Matt Holliday, Miguel Cabrera, Adrian Gonzalez, and Dee Gordon, some of the best players in baseball. He still strikes out a lot (30.1%, the eighth-highest in baseball), and his .422 batting average on balls in play is probably unsustainable. So his on-base percentage is likely to drop—but he's shown admirable patience for a rookie.

But it's not just Bryant. Anthony Rizzo's excellent walk rate (12.9%) is lower than his strikeout rate (10.0%). The former has climbed from 11.9% last year, and the latter has dropped precipitously from 18.8%.

Then there are the new acquisitions. Last year, the Cubs had two regulars with a walk rate over 10 percent, Rizzo and Luis Valbuena. This year, they have four: Rizzo, Bryant, Dexter Fowler, and Miguel Montero. David Ross, who catches Jon Lester in place of Montero, has walked 17.9% of the time.

Another way of looking at it: last year, the Cubs swung at pitches outside the strike zone 32% of the time, the tenth worst in baseball. In 2013, they were tenth-worst; in 2012, fifth-worst; in 2011, third-worst.

This year, they're swinging at balls 27.8% of the time, fourth-best.

They still strike out a lot—they have the highest strikeout rate in baseball, and the worst contact rate on pitches they do swing at. But if you have contact problems, not swinging at bad pitches is a good first step.

The one problem with walking a lot is that you're trading one safe base for the possibility of a double, triple, or home run. And as if to compensate, the Cubs are running a lot more this year.

They're running more, and they're better at it. Dexter Fowler expectedly leads the team with nine steals; more surprisingly, big Anthony Rizzo has eight, three more than he had all of last year, and two more than all of 2013. The Cubs have four players on pace for double-digit steals. Last year they had one, Emilio Bonifacio, who has zero this year for the White Sox. (The Sox, incidentally, have fewer stolen bases as a team than Anthony Rizzo, and have been thrown out more often than they've succeeded.) By Fangraphs's wSB (weighted Stolen Base Runs Above Average), the Cubs are in the black for the first time in five years. Last year, they were worst in baseball.

The Cubs' willingness to run shouldn't be a surprise. Joe Maddon came in with that reputation—but it's not just Maddon. Here's what Scott Lindblom wrote at Beyond the Box Score last year about the team's new manager:

Base running is another facet in which the manager can have influence over the game. He can do it through pinch runners (13th — not shown on chart), advancing on the base paths on an out (10th), taking an extra base on a hit, for example, going from first to third on a single (1st), attempting to steal a base (1st) or being thrown out on the base paths trying to advance (8th). Taken together, this reflects the understanding that, all other things being equal, the value of an extra base is not outweighed by the cost of giving up an out and shows an understanding of the Tom Tango Run Expectancy Matrix that is almost spooky. It also reflects that teams with lower payrolls often rely on speed to make up for the lack of power.

Tom Tango, the pseudonymous creator of that matrix? He works for the Cubs, too.

The Cubs made a lot of big news over the past few months—hiring Maddon, signing Jon Lester, promoting Kris Bryant, rehabilitating Wrigley Field. It's working out; they're a respectable 4.5 games behind the Cardinals, who have the best record in baseball but will struggle to maintain that with their ace, Adam Wainwright, gone for the rest of the season. And if the season ended today, the Cubs would be in the playoffs as a wild-card team. But for all the big news, it's the little things that are counting.