There’s a miscomprehension out there, when looking at the stats, that Joe Flacco and Case Keenum were close to identical in 2018, which is far from the truth.

So we dug into the numbers to see how the Denver Broncos new quarterback compares to Denver’s 2018 starter and how the big signal-caller stacks up against the AFC West’s other QBs.

Flacco vs. Keenum

The biggest differences between Flacco and Keenum comes down to key areas such as third-down conversions, sacks, touchdown-to-interception ratio, fumbles, and two composite metrics that analyze a quarterback’s overall efficiency—QB rating and our in-house metric, DPR.

Let’s start with their production on third down, the money down, where quarterbacks can impact the game the most as passers.

Not only did Flacco convert 40.7 percent of his attempts on third down, compared to the 31.6 percent Keenum converted a year ago, he was also more efficient on third-and-long.

This is a huge difference between the two, as opponents knew the Broncos were dead in the water once No. 4 faced obvious passing downs like third-and-long, an issue that has plagued for the former Houston stand out his entire career, even in his magical 2017 season with the Minnesota Vikings. With Flacco’s cannon for an arm, defenses have to respect his ability to let it rip deep, forcing opponents to stay on their toes on all down and distances.

So while a minimal one and a half percent difference between Keenum and Flacco might suggest they’re not that different on third-and-long, you best believe they are. In just nine games, Flacco had 42 passing attempts on third-and-long, while Keenum had 62 in 16 games. Keenum, despite those 20 additional attempts only converted 17 first downs, Flacco converted 12. That’s a sizable difference and shows just how much more Flacco can be trusted on the money down of all money downs.

The former Super Bowl MVP was also significantly more efficient on third-and-medium, which is often also an obvious passing down, converting 44 percent compared to Case’s 37.

Keenum was at his best in 2017 with the Vikings on third-and-short, but he converted a disappointing 26.7 percent of his attempts in Denver. Even in short down-and-distance with a run game that was humming, Keenum just couldn’t keep the chains moving. Flacco, who we found to be surprisingly productive in play-action situations, was the exact opposite, converting almost all the opportunities he was given, sporting a league-best 87.5 percent on third-and-short.

A former quarterback like John Elway understands that the QB makes all the difference on third down and that is exactly where Flacco separated himself from Denver’s 2018 starter.

Another key area for these two QBs is avoiding pressure, another strength of Keenum’s back in his break-out 2017 season in Minnesota, and another area in which he underwhelmed in the Mile High City. Flacco’s ability to avoid sacks, despite playing from behind in five of the nine games he started in 2018, stood out, as he was sacked on just 4.2 percent of his dropbacks while the more-mobile Keenum was brought down on 5.8 percent of his pass attempts. On third down specifically, Keenum was sacked 19 times in 2018—13.5 percent of the time he dropped back to pass, while Flacco was only taken down six times, or 6.8 percent of his third-down attempts. A big difference.

Keenum was intercepted on 2.73 percent of his throws on the year, compared to Flacco’s 1.5 percent, another noticeable difference. Keenum fumbled the ball up 11 times last season, while Flacco did so only three times. When put into a per-game rate, Keenum fumbled the ball at over twice the rate that Flacco did in 2018.

When it comes to avoiding turnovers and playing efficient situational football, Flacco was clearly superior, despite coming off a career average or slightly-less-than-average season.

So while looking at conventional stats individually might give the impression that the Broncos two QBs performed at similar rates in 2018, a deeper look shows a stark difference.

There’s no better demonstration of this than our own proprietary metric, DPR, which takes into account 18 different statistical categories. Per DPR—which does calculate turnovers and third-down efficiency—Flacco produced a solid 71.54 rating, while Keenum was a disappointing 64.55.

Digging deeper into the advanced metrics, we also found how Flacco’s air yards to the sticks—per Next Gen Stats—ranked 12th in the NFL last year to Keenum’s 28th rank. The stat quantifies vertical yards or yards thrown ahead of the line of scrimmage, and the noticeable difference helps put the two QBs similar completion percentages into context.

Intended air yards—which simply measures the average distance a pass travels in the air—also showed a similar disparity between the two, as the former Raven ranked 13th while Keenum was 28th.

Now, Keenum was still forced to take shots downfield last year, especially at the end of games, and he fared well ranking in the top-11 per completions of 20-plus yards and in the NFL’s top five for completions of 40-plus yards. However, when put into the context of per-game production, Flacco’s figures would’ve been close to identical to Keenum’s on deep throws and maybe even higher had he played from behind as often as the Broncos did last year.  

So while similar completion percentages and yards-per-attempt numbers from 2018 suggest there wasn’t much of a difference, when you consider those air yards, it’s clear Flacco was pushing the ball vertically at a consistently higher rate and still completing 61.2 percent of his passes to Keenum’s 62.3.

Another area in which Flacco did significantly better was in the red zone, where he completed 53.4 percent of his throws within the 20 to Keenum’s 46 percent—both threw 10 red zone touchdowns, though Flacco did so in seven fewer games while giving up snaps to Lamar Jackson on special packages down in the red area.

Flacco vs. the rest of the AFC West

We mentioned DPR earlier, a more valuable statistic in assessing a quarterbacks production than QB rating, which only accounts for four statistical categories, while DPR takes 18 stats into account, including fumbles, third-down percentage, sacks, red-zone percentage, and QB rating among others.

When stacked up against the other QBs in the AFC West, Flacco’s 71.54 DPR is higher than Keenum’s—who rated as the worst quarterback in the division by a healthy margin—and Derek Carr, who scored a 68.14 in 2018.

However, Flacco’s production in Baltimore was well behind Phillip Rivers’ 79.82 and Patrick Mahomes’ 91.35—the highest rated DPR by a QB in our two years of tracking the stat.

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It’s worth noting that a Kansas City Chiefs quarterback has ranked as the top passer per DPR the last two years, with Mahomes besting Alex Smith’s 81.24 from 2017 by over 10 points. Over the course of an entire season, Mahomes’ DPR is one of the best we’ve ever tracked in all the major-four sports.

All that is to say that while Flacco is a significant statistical upgrade over Keenum, he sits far behind what Mahomes and Rivers did last season.

To narrow the gap and reach the level of the two standard-bearers out west, Flacco will need significant help from the rest of the team in the form of the running game and defense, two areas in which the Broncos could be the best in the AFC West. If Denver’s play calling can also provide a boost, the way Andy Reid has for his quarterbacks in the past two seasons, that could also go a long way in getting Flacco’s production to the level of his counterparts in KC and LA.