Since the Cubs season ended on Oct. 2, Theo Epstein, Jed Hoyer and the rest of the Cubs’ front office have spent time evaluating and figuring out how to improve the Cubs for 2021 and beyond.

The Cubs have Yu Darvish and Kyle Hendricks locked in at the front of the rotation and are excited to see what Alec Mills and Adbert Alzolay can do in a full season.

The strides Alec Mills and Adbert Alzolay made have Epstein and company confident about the state of the Cubs pitching rotation in 2021.

“We were really pleased this year with the progress of Alec Mills and Adbert Alzolay,” Epstein said in his end-of-the-year press conference. “Both guys took steps forward this year.”

The Cubs were forced to turn to Mills and Alzolay in their rotation after injury struck the likes of José Quintana and Tyler Chatwood. But Epstein was pleased that Mills and Alzolay stepped in without skipping a beat. 

That’s because the duo worked to improve on their weaknesses and pitched to their strengths.

Mills’ steps forward went beyond his no-hitter in Milwaukee. He was more aggressive and showed maturation in his first full season in the big leagues.

“I thought Mills was dependable, but I think he was more than that at times,” Epstein said. “I think he showed a real ability to attack lineups, even when they’d seen him before, to incorporate different approaches into his pitching and to show some of the growth as a pitcher that is the hallmark of someone that is going to be adaptable enough to succeed as a starter for a long time.”

Mills was nearly lights-out when he went right after hitters. Opponents slashed just .174/.220/.339 after he threw a first-pitch strike. In full counts, opponents hit only .182 off of him. Getting ahead was crucial for Mills and he’ll need to continue to do that if he’s to continue to grow and succeed in 2021.

His incorporation of “different approaches” as Epstein said was seen in his changeup usage. He improved his command of the pitch in 2020, decreasing his reliance on it slightly, but using it more effectively. Here’s how Mills used his changeup in 2020 versus 2019:

Alzolay, too, showed the ability to sequence and command his pitches to effectiveness. After a Sept. 10 start against the Reds, Alzolay was sent back down to the team’s alternate site in South Bend and worked with minor league coordinator Craig Breslow and pitching coaches Ron Villone and James Ogden to add and improve his slider. Prior to working on the slider, the variance in movement and speed between Alzolay’s slider and curveball wasn’t there. So they added velocity to the slider, while tunnelling both pitches. 

The results were astounding.

In his next 2 appearances, Alzolay allowed just 4 hits, 4 walks and struck out 15 in 9 innings of work. In those 2 games, opponents did not muster a hit off his slider.

“I wanna tip my cap to the work he put in and the support he had at South Bend with Craig Breslow and all the coaches there – Ron Villone, Casey Jacobson and James Ogden and others – with the work they put in on his slider,” Epstein said. “Separating his breaking balls, adding velocity to his slider and spin and really giving him a, now, major-league weapon that he took right into some important games in the big leagues at the end of the year.

In that sense, Alzolay exceeded expectations that the Cubs front office had for him.

“I think going into the year we were hoping that Adbert could develop into a major league starter and now we see one,” Epstein said. “And he’s someone that I think is primed to slide into the rotation.”

If Mills and Alzolay continue to improve like they did in 2020, it gives some support to the front of the rotation. With Darvish, Hendricks, Mills and Alzolay, Epstein and the Cubs are feeling confident about where their starting staff sits going into 2020.