Matthew Boyd gives the Cubs another lefty starter in a rotation that is southpaw-heavy.

Boyd joins Shota Imanga and Justin Steele as likely starters on the Opening Day roster. Jordan Wicks, the Cubs’ 2021 1st-round draft pick who was in the Opening Day rotation in 2024, will be in the mix to start games, too.

So why the heavy focus on lefty starters?

Well, a clear answer is talent. Imanaga and Steele were Cy Young-caliber pitchers in 2024 and 2023, respectively, and Boyd had a 2.72 ERA in 8 starts after Tommy John surgery in 2024. The Cubs are bullish that he can build on that and be a viable member of their rotation in 2025 and 2026.

[MORE: Where Cubs rotation stands after addition of Matthew Boyd]

But another reason why the lefties could be valuable is the Cubs’ opponents. In the NL Central, the Cubs have four opponents who haven’t exactly lit the world on fire against southpaws.

Over the last two years, the Brewers, Cardinals, Reds and Pirates have all been below average (100) in weighted runs created plus against lefty pitchers. In 2024, Pittsburgh (93, 21st), St. Louis (91, 22nd) and Cincinnati (84, 27th) all ranked in the bottom third of the league in wRC+ against lefties. Milwaukee was 15th with a wRC+ of 99 against southpaws.

The Cubs play 52 games — roughly a third of their schedule — against those four teams and advantages like that can be a difference-maker. Last season, Cubs lefties had a 3.08 ERA and 1.15 WHIP against the NL Central and their opponents, compared to a 4.19 ERA and 1.32 WHIP for righties.

Some of the most fun, intriguing players in the NL Central — Jackson Chourio (93 wRC+) and Elly De La Cruz (82) — struggle against lefties. Players who thrived against lefties, like Jonathan India (126) and Paul Goldschmidt (134), have either left the division or become free agents.

There are still some boppers against lefties, for sure, but the crux of these teams returning have their woes against lefties.

[MORE: State of the Cubs: Fortifying an area of the team’s strengths]

Marginal differences can often play a big factor for teams, especially in larger sample sizes. The Cubs wouldn’t necessarily look to build a team around an advantage against, say, the Orioles or Yankees, because they don’t play them too often, but against their division, those can be the difference between a few wins throughout the season.

Again, it’s not to say the Cubs were only targeting lefties this offseason. Above all else, the most important factor is simply filling out the pitching staff with quality arms.

But the rotation appears to be set. And if it appears to be too left-handed, there’s a positive in it — one that could benefit them throughout a third of their season.