Pittsburgh Pirates vs. Chicago Cubs Prediction – September 13, 2026
As the 2026 MLB season enters its final weeks, every game carries postseason implications. On Sunday, September 13, the Pittsburgh Pirates travel to Wrigley Field to face the Chicago Cubs in a pivotal NL matchup. The WP Baseball Predictor has issued a Slight Lean on the Pirates +1.5, suggesting a close, competitive contest where Pittsburgh holds a marginal edge against the run line. Here's a full breakdown of what to expect.
Starting Pitcher Matchup: Chandler vs. Boyd
The pitching duel at the heart of this game features two arms with nearly identical peripheral profiles, setting the stage for a tightly contested affair.
Bubba Chandler (Pittsburgh Pirates)
Bubba Chandler takes the mound for Pittsburgh carrying an xFIP of 4.17, a metric that measures expected fielding-independent pitching and normalizes for home run rate. That figure indicates Chandler has been a solidly above-average starter by process, limiting his exposure to factors outside his direct control. For a Pirates team that boasts a strong overall pitching staff — reflected in a team FIP of 3.92 — Chandler fits neatly into a rotation that has consistently outperformed league norms.
Matthew Boyd (Chicago Cubs)
Opposing him is Cubs left-hander Matthew Boyd, who posts a slightly higher xFIP of 4.29. While the gap between the two starters is not dramatic, Boyd's peripheral mark does suggest he carries a marginally higher underlying risk profile than Chandler on this particular evening. The Cubs' team FIP of 4.78 — considerably higher than Pittsburgh's — further underscores a systemic pitching vulnerability on Chicago's side that extends beyond Boyd alone.
On paper, this pitching matchup favors Pittsburgh in a subtle but meaningful way, and it is one of the primary drivers behind the WP model's lean toward the Pirates covering the +1.5 run line.
Why WP's Model Favors the Pirates
The WP Baseball Predictor's Slight Lean on Pirates +1.5 is rooted in a combination of pitching and offensive context. Pittsburgh's team FIP of 3.92 compares favorably to Chicago's 4.78, suggesting the Pirates' pitching staff as a whole is better positioned to limit runs. Meanwhile, the Cubs carry the offensive advantage in this matchup, posting a team wOBA of 0.334 against Pittsburgh's 0.319 — meaning Chicago's lineup has generated more offensive value overall. However, the run-line cushion of +1.5 means Pittsburgh doesn't need to win outright; they simply need to keep the game close, a realistic outcome given their superior pitching infrastructure and Chandler's edge over Boyd in xFIP.
Injury Report: Key Absences to Watch
Injuries on both sides could influence how each manager constructs their bullpen and lineup depth late in this game.
Pittsburgh Pirates Injuries
- Braxton Ashcraft – Arm (15-Day IL)
- Kyler Fedko – Knee (7-Day IL)
- Jhostynxon Garcia – Undisclosed (7-Day IL)
- Isaac Mattson – Hip (15-Day IL)
- Esmerlyn Valdez – Hamstring (10-Day IL)
Chicago Cubs Injuries
- Dansby Swanson – Oblique (10-Day IL)
- Gavin Hollowell – Shoulder (15-Day IL)
- Corbin Martin – Undisclosed (7-Day IL)
- Trent Thornton – Ankle (15-Day IL)
The Cubs' most notable absence is shortstop Dansby Swanson, sidelined with an oblique injury. Losing a middle-of-the-order presence removes a significant offensive weapon from Chicago's lineup and could further limit their ability to pull away from Pittsburgh in a tight game.
Dark Horse Home Run Picks
Every close game has its potential game-changers. Here are the dark horse home run candidates worth monitoring on September 13.
🏴☠️ Pirates: Rafael Flores Jr.
Flores Jr. is the WP model's dark horse pick for Pittsburgh. With the Cubs carrying a bloated team FIP, there may be opportunities for power to emerge from unexpected spots in the Pirates' lineup, and Flores Jr. is the name to watch.
🐻 Cubs: Michael Conforto
On the Chicago side, veteran outfielder Michael Conforto is the dark horse selection. Conforto has the experience and power profile to deliver a big moment against a right-handed starter, making him a player to keep an eye on whenever he steps to the plate.
Final Prediction
This September matchup figures to be a low-margin, competitive game defined by pitching and situational hitting. With Chandler holding an xFIP edge over Boyd, Pittsburgh's superior team FIP providing structural backing, and the run-line cushion of +1.5 working in the Pirates' favor, the WP Baseball Predictor's Slight Lean on Pirates +1.5 is well-supported. Don't expect a blowout — expect a grind, and expect Pittsburgh to keep it close.