Here's the part you already knew: Over the summer, the Cubs added a flamethrowing reliever with high spin rates who has proven to be an absolutely dominating addition to what was already a pretty decent bullpen.
Here's the part you might not know, at least if you're not paying daily attention to the Cubs: We're not actually talking about late July acquisition Aroldis Chapman. We're talking about rookie sensation Carl Edwards, Jr., a 2011 Texas Rangers 48th-round pick who had a 4.26 ERA at Triple-A Iowa this year before being recalled mainly to boost an overworked bullpen when Dexter Fowler went on the disabled list in June.
In barely more than two months since, Edwards has proven to be so effective, so quickly, that when manager Joe Maddon needed a closer on Thursday with Chapman unavailable and previous closer Héctor Rondón injured, he turned to the rookie for his first career save opportunity. It took Edwards all of 13 pitches to tear through the Giants' Hunter Pence, Brandon Crawford and Joe Panik. If it seems like Edwards' 2.89 ERA is pretty good -- and it's more than fine -- realize that it'd be a mere 1.33 in 26 games if not for a single poor outing against St. Louis in August that inflated it by more than double.
In fact, consider this: Arguably the most dominating thing a pitcher can do is to simply throw strikes and prove that a hitter can't touch him. That's not to say that there isn't value in forcing a hitter to look foolish by chasing a bad pitch out of the zone, because of course there is. But for pure, "Here's what I've got, do something with it," there's nothing quite like looking at the list of pitchers who allow the lowest rate of contact on pitches in the strike zone. Through Monday, there have been 464 pitchers with at least 20 innings thrown the year. The leaders at preventing in-zone contact are ... let's say, impressive.
Lowest in-zone contact rate, 2016, minimum 20 innings pitched
1. 70.4 percent -- Edwin Díaz
2. 70.7 percent -- Edwards, Jr.
3. 71.8 percent -- Chapman
4. 72.7 percent -- Seunghwan Oh
5. 72.9 percent -- Sean Doolittle
Craig Kimbrel is seventh on that list. Max Scherzer and Dellin Betances are in the top 20. Diaz is quietly setting rookie strikeout records in Seattle, and any pitching list that has Chapman third must say something pretty notable about the players ahead of him. Obviously, throwing strikes that hitters can't touch is a good indicator that you're doing something very right.
For Edwards, the first thing you notice is that fastball velocity. This year, 456 pitchers have thrown at least 100 four-seam fastballs, and his 94.5 mph average velocity is tied for 68th, putting him in the top 15 percent. But if you sort that same list by Statcast™ spin rate, you'll see that Edwards goes from "good" to "great," and we've learned that a high fastball spin rate, which helps the ball defy gravity for slightly longer than the hitter expects, positively correlates to swinging strikes and popups or fly balls.
Highest four-seam spin rate, 2016, minimum 100 fastballs thrown
1. 2,674 rpm -- Andrew Bailey
2. 2,653 rpm -- Edwards, Jr.
3. 2,559 rpm -- Justin Verlander
4. 2,554 rpm -- Scherzer
5. 2,541 rpm -- Chapman
MLB average: 2,264 rpm
Now, it should be obvious that a high spin rate doesn't guarantee success, because Bailey, unable to throw strikes, washed out with the Phillies before surfacing with the Angels. But the other names there are quite impressive, and part of that is because their high-spin fastballs are difficult to make contact with. Edwards, for example, has allowed a mere .109 average on his fastball. He's allowed just a .069 average against his curveball. In what seems like the blink of an eye, Edwards has become all but unhittable by challenging hitters with a high-spin, high-velocity fastball, paired with a curveball that's effective against righties and has yet to be turned into a hit by lefties.

If it hardly seems like the Cubs needed another source of talent, that's probably true. (Edwards and National League Cy Young Award candidate Kyle Hendricks, among others, were stolen from Texas in back-to-back Deadline deals for veteran starters Ryan Dempster and Matt Garza in 2012 and '13.) But consider now what the emergence of Edwards as a viable back-end option does for the Cubs headed into October.
On Opening Day, Chicago's bullpen was Rondon, Pedro Strop, Justin Grimm, Travis Wood, Trevor Cahill, Clayton Richard, Adam Warren and Neil Ramírez. As a group, those eight pitchers gave the Cubs 303 2/3 innings of a 3.53 ERA and a 4.01 FIP, with a 24.3 percent strikeout rate and a 9.3 percent walk rate. Since the Major League average is a 21 percent strikeout rate and an 8.2 percent walk rate, the original Cubs bullpen was a bit better than average in terms of strikeouts, and below in preventing walks.
Of course, now Richard is in San Diego, Warren's in the Bronx and Ramirez is with Triple-A Rochester. Joel Peralta, Joe Nathan and Spencer Patton have come and gone. Much has changed in the Wrigley bullpen. If you were to put together a potential October relief crew of Chapman, Edwards, Rondon, Strop, Cahill, Grimm and Mike Montgomery (Rondon and Strop are both expected back from injury by October), now you're looking at 242 innings of 2.86 ERA backed by a 3.05 FIP. That collection would have a 30.7 percent whiff rate and a similar 8.7 percent walk rate.
Or perhaps Maddon would include veteran Joe Smith, who has struck out seven of the 13 September hitters he faced after a rough debut with the Cubs. Or rookie lefty Rob Zastryzny, who has allowed one earned run in his first 11 1/3 Major League innings. Or Wood, though he's had a rougher second half than first half.
The point is, suddenly Maddon has more relief options than he knows what to do with, in part because the front office made moves to go get him better choices. But for all the publicity Chapman received, the most interesting Cubs addition may have been the pitcher drafted in a round that no longer exists. When Edwards is making high-leverage October appearances, don't say you weren't given a heads up.