The Carolina Panthers waited on safety Dean Marlowe for a month. When he finally returned to the field, his troublesome hamstring held up for only 16 snaps.

Marlowe was placed on injured reserve Tuesday after he aggravated the injury in Sunday's win over the 49ers.

After impressing the Panthers as an undrafted rookie in 2015, Marlowe worked as the No. 3 safety throughout the spring. But three days before the preseason opener in Baltimore, he strained his hamstring at training camp. Marlowe then missed four weeks before returning to limited practices in Week One.

The Panthers haven't yet decided on a corresponding move. They have a pair of safeties — Marcus Ball and Travell Dixon — on the practice squad. They could also get back in touch with a guy like Donte Whitner now that veteran contracts are no longer guaranteed.

But while Marlowe's season appears over, it may not be. That's because of a rule change passed in March that went largely unnoticed.

Last year, the Panthers put defensive end Charles Johnson on the injured reserve/designated for return list like they did with fullback Mike Tolbert a year earlier. That list no longer exists, but teams can still bring one player off injured reserve as long as he's been out at least six weeks. The difference is they no longer have to designate a player ahead of time.

So, if the Panthers get through October relatively healthy, and they're still interested in having Marlowe on the roster, they could do that then. Or they could bring someone else back from IR.

It's rare when an NFL rule change is sensible and intriguing, but this one is both.