Cubs setup man Phil Maton diagnosed with partial tear in right patellar tendon

Phil Maton’s season with the Chicago Cubs has taken another turn. The club’s setup man, who has already spent time on the injured list multiple times this year for right-knee issues that were previously described as tendinitis, has now been diagnosed with a partial tear of the patellar tendon in that same knee, according to a report from Meghan Montemurro of the Chicago Tribune that was relayed by MLB Trade Rumors.

Maton’s knee troubles have been a recurring theme for the Cubs’ bullpen. This is not the first time he has been sidelined this season, and the new diagnosis reframes what had been treated as a more typical tendon problem into something more structural. The patellar tendon is central to knee extension and load tolerance, so a partial tear can directly affect the mechanics pitchers rely on to generate pace and repeatability.

The report also indicates that Maton received a platelet-rich plasma, or PRP, injection about three weeks prior. That timing matters because PRP is often used as part of a conservative treatment plan for tendon injuries, and the Cubs will now have to evaluate whether the knee responds well enough to allow a gradual, bullpen-based return rather than continued downtime. At this stage, the return timeline remains uncertain.

According to the reporting, it is unclear if Maton will be available to return this season. The Cubs are expected to make a decision later this month, meaning roster planning for the back end of games may need to adjust in the near term regardless of whether Maton ultimately returns in 2026.

For Chicago, the practical impact is about leverage. A setup role is where teams typically protect leads and set up the ninth inning, so losing a dependable late-inning arm can force managers to redistribute innings across higher-leverage relievers who may not have the same endurance, pitch mix, or feel late in the game. Even if Maton misses only a short stretch, the bullpen shuffle can have ripple effects for usage patterns in subsequent series.

What to watch next is the Cubs’ internal decision-making process around Maton’s rehab and the sequencing of bullpen assignments in games where late leads are on the line. If the Cubs determine the injury requires more time, Chicago will likely lean more heavily on other relievers to bridge from the middle innings to the closer, while also monitoring workload so the bullpen is not worn down before postseason positioning is fully settled.