Rob Gronkowski’s Risk Assessment and Draft Value

Since New England Patriots’ Rob Gronkowski entered the NFL in 2010, he has been one of the game’s most dominant tight ends. From 2010-’12, Gronkowski led the league in standard-scoring fantasy points per opportunity (carries + pass routes) among tight ends that played in at least 25% of offensive snaps for the season.

He also led the league in receiving touchdowns by a tight end during that same time. The most notable being 2011 when set the NFL single-season record for receiving touchdowns by a tight end (17).

Furthermore, in both the 2011 and 2012, Jimmy Graham and Gronkowksi finished first and second in total standard-scoring fantasy points for the regular season.

However, none of those objective measures remained true for him in 2013. While Graham continued his elite fantasy production, Gronkowski had a difficult time getting onto the field.

He missed the first six games of the season due to lingering issues from multiple offseason forearm surgeries —in conjunction with issues stemming from his microscopic lumbar discectomy surgery that was also performed in the offseason. He then suffered a torn ACL and MCL in Week 14, and missed the remaining three regular season games. In total, Gronkowski played in only seven games last season.

After considering Gronkowski’s injury-ridden 2013 season, the question that should be on every fantasy player’s mind is: what are reasonable expectations for Gronkowski’s fantasy value for the 2014 season?

To accurately answer that question, three things need to be considered: the probability he will be injured again this season, the probability he will have a decline in production following his ACL/MCL surgical repair, and his current market value heading in fantasy drafts.

First, take a look at Gronkowski’s past injury history. He missed his entire college junior season (2009) at the University of Arizona due to having a back surgery. After being drafted by the New England Patriots, the injuries and surgeries continued to add up.

Each injury comes with its own recurrence rate. Here are the recurrence rates of each of his significant injuries in chronological order:

• Gronkowski’s high (syndesmotic) ankle sprain from 2011 has undoubtedly decreased the long-term stability of the ankle. It has also increased his vulnerability for future non-contact knee injuries. The recurrence rate of a high ankle sprain has been shown to be approximately eight percent in a three-years period from the time of the initial injury.¹

• The forearm fracture and subsequent infections appear to have healed, and should not be of any major concern for Gronkowski from this point forward.

• Gronkowski’s herniated lumbar disc in 2012 is likely associated to the back issues he suffered during his junior year in college. He had a microscopic lumbar discectomy, and the reported incidence rate of a recurrent disc herniation after this procedure is also approximately eight percent.^2,3

• The hamstring strain he suffered during the 2013 regular season should not have come as a surprise. A person with a history of lower extremity radiculopathy – a common symptom of a lumbar disc herniation – has an increased chance of suffering a hamstring strain. Unfortunately for Gronkowski, hamstring strains have a high recurrence rate: 12 to 31 percent.⁴

• Since tearing his ACL/MCL in Week 14, Gronkowski had both ligaments surgically repaired. It is still unknown whether he will be ready for Week 1 of the 2014 regular season. What is known, however, is he will be at a much higher risk of sustaining another knee injury once he does return to play. An athlete with a prior recent ACL injury (within the previous 12 months) is 11.3 times more likely to injure their graft or contralateral ACL than an athlete without a history of an ACL tear.⁵  Additionally, an athlete with a recent ACL injury has a 29.5 percent chance of sustaining another ACL injury within 24 months of returning to play.  And the vast majority of the second injuries are to the opposite knee.⁶ To make matters even worse for Gronkowski, a risk factor for future knee injuries is a history of ankle injuries.

To summarize this data quickly and bluntly, Gronkowski has a significantly higher risk for future injuries than most NFL players.

Now, lets look at what level of future production we should expect from Gronkowski after looking at the evidence.

• A study showed that a cohort of NFL players who underwent a microscopic lumbar discectomy, and then returned to play, did not have a significant decline from their pre-injury levels of production. ⁷

• There is no significant evidence that would indicate that Gronkowski’s previous hamstring strain, hip injury, high ankle sprain, or forearm fracture will impede his on-field production—besides the aforementioned increased chance having a re-injury.

• On the other hand, there is evidence that shows players returning from an ACL repair have significant declines in production. A study found that NFL running backs, tight ends, and wide receivers that are returning to play following an ACL repair commonly see a decline in production (total yards and touchdowns) of about one-third.⁸

This would also be a good time to point out that Adrian Peterson’s production after his ACL repair is an extreme outlier from the norm. It should be considered a rare exception, and be no indication of Gronkowski’s future production.

Now, lets look at how Gronkowski is currently being valued in fantasy drafts. Then, we will use our aforementioned injury analysis in conjunction with Value-Based Drafting (VBD) calculations to determine an appropriate value for him.

According to myfantasyleague.com’s (MFL) 2014 average draft position (ADP) results, Gronkowski’s average pick position at the time this article was written is 29.38 overall in non-IDP non-PPR redraft leagues of any size. That would put him somewhere in the third round of most fantasy leagues.

Because the first-three picks of a fantasy draft should be players with high upside and minimal risk, Gronkowski is overvalued currently due to his high injury risk. Lets now see what the VBD calculations show.

Using the “Top 100 Method” –first referred to by Joe Bryant and David Dodds—to determine the baseline value for each position, we will determine Gronkowski’s VBD score.

We will continue to use MFL ADP results for 2014 non-PPR non-IDP redraft leagues.

And we will calculate the VBD scores for a 10-team non-PPR non-IDP redraft league with a team structure detailed in the following graph.

Using the “Top 100 Method,” the following players will be used as the baseline for players of replacement value.

With these baseline values, and using PFF fantasy projections for 2014, the following VBD scores were calculated:

Gronkowski’s VBD score places him at number 60 overall. This is far outside the VBD of a player that should be taken in the third round.

And it is worth noting that his projected points for the season were based on the notion that he would play 15 games this season: quite a generous projection.

After considering the aforementioned recurrence rates of his previous injuries, my conservative projection for the number of games he will play this season is 12. This would make Gronkowski’s value for the season be 12 games of his production—which is expected to be less than recent years—plus four games of replacement value (i.e. Charles Clay’s projected 5.75 points/game). Therefore, my projection would place Gronkowski’s VBD (52) at 64th overall.

Gronkowski’s high risk of injury and low VBD score make him a fifth-to-sixth round investment this year’s fantasy drafts. Because he would almost certainly be off most draft boards by then, you should make other plans for your tight end position in 2014.

References

1)   Nussbaum ED, Hosea TM, Sieler SD, et al. Prospective evaluation of syndesmotic ankle sprains without diastasis. Am J Sports Med. 2001; 29(1):31-5.

2)   Takahashi H, Iida Y, Yokoyama Y, et al. Recurrent Lumbar Disc Herniation after Microendoscopic Discectomy. J Spine Neurosurg. 2014; 3(3).

3)   McGirt MJ, Ambrossi GL, Datoo G, et al. Recurrent disc herniation and long-term back pain after primary lumbar discectomy: review of outcomes reported for limited versus aggressive disc removal. Neurosurgery. 2009; 64(2): 338-44.

4)   Heiderscheit BC, Sherry MA, Silder A, et al. Hamstring strain injuries: recommendations for diagnosis, rehabilitation, and injury prevention. J Orthop Sports Phys Ther. 2010;40(2):67-81.

5)   Smith HC, Vacek P, Beynnon BD, et al. Risk Factors for Anterior Cruciate Ligament Injury: A Review of the Literature—Part Hormonal, Genetic, Cognitive Function, Previous Injury, and Extrinsic Risk Factors. Sports Health. 2012; 4(2):155-161.

6)   Paterno MV, et al. Presentation at the 2013 annual meeting of the American Orthopaedic Society for Sports Medicine.

7)   Hsu WK. Performance-Based Outcomes Following Lumbar Discectomy in Professional Athletes in the National Football League. Spine. 2010; 35(12): 1247-’51.

8)   Carey JL, Huffman GR, Parekh SG, et al. Outcomes of Anterior Cruciate Ligament Injuries to Running Backs and Wide Receivers in the National Football League. Am J Sports Med. 2006; 34(12): 1911-1917.