The three pitchers who are fueling the Cubs' excellent rotation

However, the dominant outing served as a reminder of Chicago's pitching talent and the starters' dramatic improvement from last season. Smyly and the rest of the starting pitchers have stymied hitters this season. Is the staff for real?

Last season, Chicago pitching finished in the bottom third of the league in ERA (4.00) and WHIP (1.3) as it gave up the sixth-most runs in the league. Through 24 games in 2023, the staff is top 10 in ERA (3.51) and WHIP (1.17) and has allowed the third-fewest earned runs in MLB. 

Chicago has done this with largely the same pitching staff as last season -- the front office sent Adrian Sampson to the minors and moved Keegan Thompson to the bullpen while signing Jameson Taillon and calling up Hayden Wesneski.

Even with Kyle Hendricks recovering from injury, this rotation has surprised many behind three pitchers in particular. 

Smyly, Marcus Stroman and Justin Steele are a three-headed beast for the Cubs, combining for a minuscule 2.16 ERA. All three are playing at a high level, but it's worth diving deeper to see if this is luck or sustainable change. 

Smyly has never been an ace, sporting a 4.10 career ERA entering this season. Despite never being a household name, he owns an elite 0.929 WHIP in 2023. The 33-year-old southpaw hasn't seen this level of success since 2014-15.

Smyly's 2023 success can be attributed to a pitch mix change. According to Baseball Savant, Smyly went from throwing his cutter 20% of the time in 2022 to 5% this season. Historically, opponents have crushed his cutter, so a change was in order. Smyly simultaneously increased his sinker and curveball usage, which has led to a sharp decrease in hard-hit balls. 

With the meaningful alterations to his approach, Smyly could easily continue his 2023 success. Stroman, however, doesn't have such a rosy outlook. 

A 2019 All-Star selection, Stroman is a good pitcher. From 2019-22, the righty posted a 3.23 ERA. (He sat out 2020 as a COVID opt-out.) But his torrid 2023 start doesn't seem sustainable.

Stroman's 2.17 ERA is upheld due to opponents having a .214 batting average on balls in play against him, far below the .297 league average and Stroman's .300 career BABIP. Although his start to 2023 has been incredible, this number points toward regression as the season goes on. 

One of the most unlikely performances so far is Steele's. A fifth-round pick in the 2014 MLB Draft, he didn't even crack Chicago's top 20 prospects the year before his 2021 debut. After a rough debut season, Steele burst onto the scene in 2022 with a 3.18 ERA.

Steele has continued mowing down hitters and sports a National League-leading 1.19 ERA through five 2023 starts.     

The 27-year-old pitcher established himself as one of the best in baseball recently. Even though he likely won't maintain a historically low ERA, Steele is obviously talented and could be a front-line starter for years. 

With contributions from Smyly, Stroman and Steele, the rotation looks formidable, especially with the return of Hendricks looming. Hendricks completed a rehab start Thursday.