The Numbers Behind the Deception
Trent Thornton has appeared in 40 games for the Chicago Cubs this season, posting a 2.38 earned run average that belies the modest role he has been given.
His 1.3 win‑probability added (WPA) places him above the average reliever and trails only Ben Brown and Javier Assad among Cubs pitchers in leverage‑adjusted impact.
A volatile arm in the middle
The Cubs’ other key middle reliever walks nearly 10% of opposing batters and has surrendered only 14.9% of the time, a combination that has left managers uneasy about the bullpen’s stability.
That reliever also struggles with barrel avoidance, having allowed four home runs already and flirting with double that figure as the season progresses.
Mechanics that mislead
Thornton’s pitch mix includes a rare spin‑mirroring technique that makes it difficult for hitters to differentiate a fastball from a breaking ball by spin alone, adding a layer of deception.
His curve and sweeper, despite sharing similar spin directions, generate unexpected movement, while his four‑seamer behaves as a cut‑ride pitch and his sinker runs more arm‑side than anticipated.
The cutter, featuring backspin, veers glove‑side, but the lack of extreme velocity or sharp movement results in frequent barrel contact, often sending well‑struck balls to the warning track.
Ground‑ball rates are high, yet the balls tend to die near the warning track rather than being cleanly fielded, limiting the effectiveness of the approach in high‑leverage October scenarios.
Injuries to other arms could open the door for fresh options, but for now the Cubs are willing to keep Thornton in the mix, recognizing that his deceptive qualities still yield results.