CHICAGO -- It was almost a perfect-world example of how the Cubs' run prevention planning is supposed to work. With Alec Mills' no-hitter on the line, Chicago's defense was forced to adjust on the fly when an unexpected scenario surfaced.

Jace Peterson stepped into the batter's box for the Brewers on Sept. 13, and the Cubs' defenders peered toward the dugout. Shortstop Javier Báez, specifically, was looking to bench coach Andy Green's instructions on where to position himself on the infield dirt with the 27th out at stake.

"You do the work you do for moments like that," Cubs pitching coach Tommy Hottovy said this week. "You never know."

Peterson did not register a plate appearance since Sept. 6, but the Cubs' strategists (Hottovy and Green, along with Cubs coach Mike Borzello and run-prevention coordinator Brad Mills) did their homework just in case. Green motioned for Báez to move up the middle, behind Mills, just to the shortstop side of second base.

Mills fired a 3-1 sinker low and away, Peterson chopped the pitch up the middle and Báez let out a howl as he gloved the ball and threw it to first base. The no-hit celebration took off from there.

"That is the prime example of what we try to accomplish," Hottovy said. "It's not like we're trying to go out and throw no-hitters every game -- that's not realistic -- but to do it in the way that Millsy did, with such few swing and miss, such few strikeouts. ... That was just a really cool moment for everybody involved.

"Obviously, of course, for Millsy and the players that were involved, but everybody behind the scenes, too, who kind of had their fingerprints all over a lot of it."

This all relates to the current state of the Cubs' rotation, because all that scouting, planning and positioning will be just as critical for the club in 2021 as the pitches that are thrown. The trade that sent Yu Darvish to San Diego last month removed an ace from the rotation, and changed the dynamic of Chicago's staff.

Losing Darvish will make the hill to October a steep one, and now the Cubs' rotation (still in need of depth) is led by Kyle Hendricks, Zach Davies (acquired from San Diego) and Mills. A potential issue with that trio is that all three are similar sinker-changeup righties who rely on precision over power.

The Cubs still think they can make it work.

"We've had a lot of success with pitchers that can throw a bunch of pitches for strikes, can really control bat speed," Cubs president of baseball operations Jed Hoyer said in the wake of the Darvish deal. "I think our pitching infrastructure has done a fantastic job of acquiring those types of pitchers and even making them better. So, from that standpoint, I think a guy like Davies will flourish with us."

Here were their average sinker velocities in 2020, per Statcast:

Mills: 90.0 mph

Davies: 88.4 mph

Hendricks: 87.3 mph

Looking at pitch usage in '20, Davies threw the most sinkers of the three at 42.2 percent, followed by Hendricks (34.4 percent) and Mills (33.2 percent). Davies featured the most changeups by far (41.3 percent), followed by Hendricks (28.9 percent) and Mills (16 percent).

That difference in changeup use starts to show the ways in which the pitchers are different. Both Hendricks and Mills throw four-seamers as well, while Davies mixes in a cutter. Mills has a slider and slow curve, and Hendricks' curve has turned into a real weapon over time.

Hottovy was quick to note those differences, adding that Hendricks is probably the best of the three at pitching up in the zone. Davies, meanwhile, had the highest changeup pitch value (11.0) among qualified MLB starters last season, according to Fangraphs. Hottovy also pointed out that it would be rare to have Hendricks, Davies and Mills all pitch in the same series this year.

"Looking at them on paper and looking at them physically," Hottovy said, "you see a lot of similarities. But, what we try to do is identify the things that they do really well. What they all do really well is command the baseball. There's something to be said for guys that have the ability to move the ball around and pitch to hitters' weaknesses, attack and get weak contact."

It is worth noting that the final rotation puzzle has not been assembled, though the Cubs are not playing at the top-tier of free agency this offseason. Any additions will likely be made with depth in mind, and Chicago may also use '21 as a chance to take a look at some of the less-experienced, internal options.

"There's going to be a lot of innings to be had," Hottovy said. "And we're going to need guys to step up and carry some of that."

Under manager David Ross last season, the Cubs took home the Rawlings National League team Gold Glove Award after pacing the Senior Circuit with a 21.9 defensive index score. As a team, the Cubs registered 23 Defensive Runs Saved and had 15.8 Defensive Runs Above Average, per Fangraphs.

Maintaining that defensive performance will be imperative in '21, and Mills' no-hitter showed how it can work when everything comes together to near perfection. Per Fangraphs, Mills had a one-in-9,600 odds of throwing a no-no based on batted-ball data. He had only five swings and misses out of his 114 pitches, but both he and the defense were precise, recording at least one out at each position.

"When you have guys that can command the baseball," Hottovy said, "and you have a good idea of where the ball's going to be thrown, then it does let you be maybe a little bit more aggressive and a little bit more pointed with your positioning, because you're trusting that the pitcher can execute.

"Luckily for us, we've just had more of those type of guys in our system that we're trusting are going to execute the pitch, trusting they're going to be able to pitch to a game plan and then let our good defenders behind them take care of the rest."