Gronkowski's race to replace Gonzalez as greatest TE complicated by injuries

Rob Gronkowski's ability to navigate space in the open field, breeze by unsuspecting defenders with his switch of pace, and proficiency in the red zone turned him into a weapon previously unseen in the NFL. Gronkowski rattled off four first-team All-Pro seasons in a five-year span, leading many to prematurely claim that he already is the best tight end of all time.

Related: Patriots restructure Gronkowski's deal, can be NFL's highest-paid TE in 2017

Projections can often be fickle and cruel, and though Gronkowski returns from back surgery to a New England Patriots team that appears to be virtually unstoppable, the 28-year-old is embroiled in a race against time if he is to stand alone among tight ends.

Tony Gonzalez played until he was 37 and until he's clearly unseated, Gronkowski faces an uphill climb.

Gronkowski hasn't played a full season since 2011, when he posted 90 receptions for 1,327 yards and 17 touchdowns, all career bests. During the 2011 AFC Championship Game, Gronkowski suffered a high ankle sprain, which rendered him largely incapable of his usual magic during Super Bowl XLVI. At the time, few would've predicted Gronkowski's horrific run of injuries that have stagnated the trajectory of an all-time great.

Here's how Gronkowski has fared with ailments since:

Gronkowski celebrated his 28th birthday on May 14, and he can no longer be billed as one of the NFL's brightest young stars, now entering the coming season as an established veteran, replete with a nauseating injury history. He's always proven to be a phenomenal athlete, but in trying to chase down Gonzalez for the title of greatest tight end of all time, he'll need to remain uncharacteristically healthy.

Here are Gronkowski's career statistics after seven seasons ...

... compared to Gonzalez's career output:

What can be inferred from the stats? Gronkowski has played just under a third of the regular season games Gonzalez did and still trails by 920 receptions. Gronkowski still has a reasonable chance of catching Gonzalez in receiving yards, but will need to maintain his average of 870 yards per season for over 11 years to come within striking distance. It's far more likely Gronkowski surpasses Gonzalez in touchdowns, but even then he'll need to maintain his average of 9.7 touchdowns per year to eclipse Gonzalez.

Gronkowski's career poses a rather perverse parlor game for football historians: Would you rather have four transcendent seasons and two Super Bowl victories with Gronkowski, or 14 excellent Pro Bowl campaigns from Gonzalez? All of this to say nothing of Antonio Gates' sustained excellence while he continues to operate as a functional tight end. Ascending through the annals of history can't be done with narrative alone.

The intangible argument is where blocking factors in, as Gronkowski is superior in this category to the other great tight ends - it was the one weakness during the decorated careers of Gonzalez and Gates. If the totality of the position matters, Gronkowski is the most complete tight end ever. But ultimately, their legacies may be determined by the raw statistical output.

None of this is to say that Gronkowski won't become the best tight end of all time. Armed with a legendary quarterback at his side, and with the Patriots making numerous moves to bolster their passing game this offseason, few would be surprised if Gronkowski continues his march to greatness. Yet, despite his perpetually youthful demeanor, the clock is ticking for Gronkowski to reach the heights many predicted for him five years ago.