Jay Cutler doesn't change Dolphins' 2017 season outlook

'Crazy 48 hours' led to Cutler signing with Dolphins (2:14)

Jeff Darlington describes the timeline of events that resulted in Jay Cutler agreeing to a one-year, $10 million deal with the Dolphins. (2:14)

By agreeing to sign Jay Cutler, the Miami Dolphins were able to keep their middling 2017 prospects mostly steady after Ryan Tannehill reinjured his left knee in practice last Thursday.

That's the good news for Miami.

To lure Cutler out of retirement, however, the Dolphins will pay the 34-year-old quarterback $10 million, per ESPN's Adam Schefter, when they already had a backup quarterback just as capable as Cutler on the roster.

Football Power Index sees Cutler as a downgrade, but a slight one, relative to Tannehill and has dropped the Dolphins' projected win total from 7.3 to 7.0. That projection includes the assumption that Tannehill is out for the season.

One benefit of signing Cutler is that he has already played in Adam Gase's system when the Dolphins' coach was the offensive coordinator in Chicago in 2015. But backup Matt Moore has also played under Gase, starting four games last season, including the wild-card playoff loss to the Steelers.

Had the Dolphins foregone the added expenditure of signing Cutler, they wouldn't have been much worse off. FPI thinks the difference between the Dolphins playing 16 games with Cutler as a starter compared to 16 games with Moore is roughly .3 wins. And frankly, in their most recent play, Moore has outplayed Cutler.

To put the Dolphins' backup, who has played only intermittently throughout his career, on the same scale as more experienced quarterbacks such as Cutler, we can compare the players' expected points added per play over a recent sample of action plays. Because Total QBR divides credit between quarterbacks and the rest of the offense, we can assign an expected points added figure to each QB.

Over the past 500 action plays, Moore averaged .102 EPA/P, better than Cutler at .079 over the same span. That was a little better than Tannehill, as well, and some of the other possible options at quarterback for the Dolphins, such as Colin Kaepernick, Brock Osweiler or Robert Griffin III. For context, Aaron Rodgers averaged .159 EPA/P over his past 500 plays, and Blaine Gabbert averaged .058 over his.

Five hundred action plays are a fairly small sample -- a little less than a full season's worth -- but then again, Moore doesn't have much of a sample size in his career. If we expand the sample to their past 1,000 action plays, Cutler jumps ahead of Moore and Tannehill by a little bit.

Granted, aside from three starts last season, Moore basically hasn't played since 2011. While that might make it harder to project his play going forward and make someone like Cutler seem more appealing, it is worth noting that the former Bears quarterback -- who missed 11 games with thumb and shoulder injuries last year -- is a little older than Moore and therefore slightly more likely to be on the decline. Given that, it's worth noting that in Cutler's most recent play -- his last 250 action plays -- his EPA/P took a nosedive all the way down to .049.

The larger point is that, while the number can change depending on how wide a lens we take, any advantage in projected play that Cutler holds over Moore is slight. Given that FPI already thinks Miami is a long shot to make the playoffs (16.6 percent chance), whatever edge the Dolphins gained by spending $10 million on Cutler most likely will be for naught.

Hank Gargiulo contributed to this story.