Cubs starting pitchers could have a 'long ball' battle to overcome this season

The starting rotation was a consistent strength for the Chicago Cubs last season. So far this offseason, the front office has added veterans Colin Rea and Matthew Boyd to the mix. They will start the year with Justin Steele, Shota Imanaga and Jameson Taillon locked into the rotation, with a mix of Javier Assad, Jordan Wicks, Rea and Boyd rounding out the starting five, barring any further moves or internal developments (i.e. Ben Brown).

While this staff can and should still be solid, there could be a bit of a home run concern with this group.

Last season, baseball's average HR/9 (home runs per nine innings) was 1.12. Unsurprisingly, these numbers have fluxed over the years based on the offensive environment in baseball. Since 2016 within the Statcast Era, the average HR/9 has been within the 1.1-1.4 range; the height being the "Juiced Balls" years from 2017-2020. Looking at recent data, the average HR/9 in a season over the past three seasons is roughly 1.13.

Keeping that in mind, last year three current Cubs starters were among the 30 highest-qualified pitchers in HR/9. Rea (1.56), Imanaga (1.4) and Taillon (1.14). Between them, that's 77 home runs given up in 506.1 innings pitched which equates to ~ 1.37 HR/9. All three were among the 21 qualified pitchers in baseball with a 40+ percent fly-ball rate last year.

Taillon's flyball rate since 2021 has been consistently 40+ percent, which was not the case pre-injury (2016-2019) when he fell within the 27-31 percent range, thus higher HR/9 (avg 1.38 since 21') rates over the past four years compared to his time in Pittsburgh. A pattern has clearly developed.

Imanaga has always been a fly-ball pitcher going back to Japan; home runs were expected and are just part of his game. We cannot let this diminish these three pitching to a combined 3.49 ERA last year. They worked around the long balls very effectively as they all had exceptional command to help limit the damage -- each individual averaged under 3.0 BB/9. This just shows home runs were part of their games.

In addition, Boyd is a career 1.6 HR/9 pitcher with 157 home runs surrendered in 908.1 career innings. In 2019 he gave up an American League-leading 39 home runs, followed up by an MLB-leading 15 home runs in the shortened 2020 season. Again though, to be fair, in a small sample size last year (39.2 innings) he only gave up four homers. How that will translate into 2025 remains to be seen.

Assad pitched just shy of 150 innings last year (147) and gave up 20 homers (1.2 HR/9), with 16 of them surrendered on the road. While the sample size was small for Wicks last year, he surrendered nine homers in 46 innings (1.8), although, four came in a disastrous start against the Dodgers.

The exception is Steele, who is known for keeping the ball in the yard. He is a career 0.9 HR/9 pitcher and was the best in that category in the National League in 2023 (0.7). Over his past 78 starts (427 innings) he sports a 0.7 HR/9, giving up just 34 homers total in that span.

One might also ask how Wrigley Field's physical environment will play in 2025. Last season was notably friendly to pitchers, with the Friendly Confines carrying the lowest home run factor environment the park has had going back to 1998. It did not take data and charts for fans to sit and watch numerous fly balls die at the warning track after being knocked down by the wind. How the weather plays in 2025 can make an impact, especially if the wind blows out more this summer.

So how concerning is all of this? It's something that might be a pain with this group of pitchers but not necessarily cripple them. As mentioned before the likes of Steele, Imanaga, Taillon and Rea possess good command and one of the best ways to limit home run damage is not walking guys. Even Boyd has a sub-3.0 BB/9 in his career. Solo homers do not beat you as often as three-run homers, and these guys can still keep you in games if the traffic is limited.