Josh Rosen was terrible as a rookie, and his statistical performance is not debatable. He was the worst passer in the NFL by ANY/A and also the worst quarterback according to ESPN’s Total QBR metric. Statistically, Rosen was awful, and there’s little more to add.

Now, does he have excuses? Absolutely. As Bill Barnwell wrote, Rosen faced some pretty rough circumstances last year, particularly when it came to his offensive line.

Other rookie quarterbacks have started their careers behind porous offensive lines, of course, but not to this extreme. By the end of last season, the Cardinals had lost all five of their starting linemen to injuries. During the second half of 2018, the five linemen who took snaps most frequently protecting Rosen included a pair of rookies (third-rounder Mason Cole and seventh-rounder Korey Cunningham), a player signed off Minnesota’s practice squad (Colby Gossett) and a pair of veterans who were cut by teams and almost immediately stepped off the street and into Arizona’s starting lineup (Oday Aboushi and Joe Barksdale). It’s one thing to have a relatively untalented line, but the Cardinals were starting guys who barely knew the playbook at times.

Now, given that we know Rosen was terrible as a rookie, how likely is he to still turn out to be a good quarterback?

The Eight That Turned It Around

Since 1967, there have been 8 quarterbacks who were drafted in the first round, played more than a handful of snaps as a rookie, were very bad, and then one day became a good quarterback.

They are: Terry Bradshaw, Troy Aikman, Eli Manning, Matthew Stafford, Jared Goff, Donovan McNabb, Bert Jones, and Alex Smith.

All 8 quarterbacks had era-adjusted passer ratings of under 50 as a rookie; they averaged a collective 39.1 era-adjusted passer rating, slightly worse than what Rosen (40.5) averaged in 2018. All 8 quarterbacks finished at least 2.00 ANY/A worse than average; collectively, they were 3.07 ANY/A worse than league average, slightly worse than Rosen’s -2.79 RANY/A in 2018.

The Eight That Didn’t Play

Another 8 quarterbacks combined to throw 144 passes — under 30 per quarterback — as rookies. After one season, we didn’t know very much about Aaron Rodgers, Patrick Mahomes, Daunte Culpepper, Philip Rivers, Carson Palmer, Steve McNair, Ken O’Brien, or Chad Pennington, but all 8 quarterbacks turned out to be, at their peak, very good (or better) NFL quarterbacks. (In addition, Steve Young and Jim Kelly went to the USFL, but counting them feels like a bridge too far.)

Is it fair to lump Rosen in with them? I’m not sure. It comes down to how you view evidence of bad compared to no evidence at all. On the surface, no evidence sounds better, but one could argue that with Rosen, we can at least say he was better on the 2018 Cardinals than Sam Bradford (who had worse statistics and played before the offensive line crumbled). A year into Pennington’s career, we knew nothing more about his pro potential than we did on draft night. For Rosen, we know… how much more about his pro potential? It’s tough to say.

The Seven Immediate (And Future) Stars

This is probably the smallest group: which 1st round quarterbacks played a substantial amount of time as rookies, played well, and then had another big year? This is a group of just 7 quarterbacks: Dan Marino, Peyton Manning, Matt Ryan, Ben Roethlisberger, Andrew Luck, Cam Newton, and Deshaun Watson. If not for injury, we would probably have Greg Cook and Robert Griffin on this list, but neither came close to matching their rookie performance ever again.

Played poorly as rookies, never became good — All 18 Of Them

There are 18 quarterbacks in the sample who threw at least 200 passes as a rookie, were bad, and never had anything resembling a good season.

Eight of them were actually not terrible as rookies: Matt Leinart, Patrick Ramsey, Teddy Bridgewater (too soon?), Cade McNown, Heath Shuler, Brandon Weeden, Steve Walsh, and EJ Manuel all finished between 0 and -1.00 RANY/A as rookies. The other 10 — Tim Couch, Rick Mirer, John Reaves, Joey Harrington, Kyle Boller, Mark Sanchez, Christian Ponder, Blaine Gabbert, Steve Fuller, and Ryan Leaf, were really bad as rookies and stayed that way.

The Rest

A few quarterbacks who would go on to have at least one very good season — Jim Everett, Vinny Testaverde, Jay Cutler, Tommy Kramer, Doug Williams, Archie Manning, and Michael Vick — don’t fit nearly into any one category. For the most part, they threw between 100 and 200 passes and had average passing numbers, so they simply had rookie seasons that didn’t resemble Rosen’s at all. Also, Josh Freeman had an awful rookie year but a great second year, but counting him as a “plus” for Rosen seems weird. I also discarded all the players like Carson Wentz and John Elway, who had below-average seasons as rookies but were clearly much better than Rosen.  And, of course, about half of all rookie 1st round quarterbacks since 1967 didn’t even throw 200 passes, so there are many more names that are not going to be discussed (most didn’t become stars, though, like the Mahomes tier).

Where does that leave us?

Good question!  The Aikman tier gives Rosen some hope, and if you are feeling generous, you might want to include the Mahomes tier, too. But there are also a number of bad quarterbacks who stayed bad. So let’s approach it from the other perspective.

Rosen became the 11th quarterback to meet these three criteria:

• Get drafted in the 1st round since 1967
• Throw 200+ passes as a rookie
• Finish at least 2.00 ANY/A worse than league average

That tier includes four clear busts: Ryan Leaf, David Carr, Blaine Gabbert, and Steve Fuller. And while less clear, I think it’s pretty fair to include a fifth player, Blake Bortles, into the bust tier.

On the other hand, here were the other 5 quarterbacks: Terry Bradshaw, Jared Goff, Donovan McNabb, Matthew Stafford, and Troy Aikman.

Does this mean Rosen has a 50% chance of becoming a Pro Bowl quarterback? At a minimum, it seems like his odds are lower than say, that of Sam Darnold and Josh Allen, two players drafted a few picks ahead of Rosen who also played better as rookies. So with Rosen, I’ll give a copout answer: if he gets enough chances, he’ll probably have a good year.

Why do I say that? Alex Smith, who threw 165 passes as a rookie, kept getting chances because he was a former number one pick. If Rosen continues to get starting jobs, there’s a good chance he’ll eventually have a strong year. It’s not a coincidence that all five quarterbacks listed above were top-2 picks, and those players tend to get second, third, and fourth chances. Rosen doesn’t have that luxury, particularly now that he’s in Miami. Someone like Cade McNown was bad as a rookie, bad in year two and then never played again in a regular season game. And McNown went to UCLA and was traded to Miami after busting with the team that drafted him.

But it’s certainly too early to close the book on Rosen’s career. Because while he could be the next McNown, his career trajectory is also following that of another Bruin in Aikman.