Rob Gronkowski is the top fantasy tight end in the NFL. In fact, it's not particularly close. 

If we go by ESPN standard scoring, he scored 178 fantasy points last season, despite not playing in the last game of the season. To put that in perspective, that is 30 points more than the next best tight end, Antonio Gates, and 41 more than third-place finisher Jimmy Graham. Gates is suspended for the first four games of this coming season. Graham is moving from a New Orleans Saints team that passed the ball 62% of the time last season (fourth in the NFL) to a Seattle Seahawks team that did so 46% of the time (last). The gap between Gronkowski and the field is quite large.

Judging by Gronkowski's average draft position, it is pretty clear that most fantasy football participants would agree. In Yahoo leagues, Gronk is being selected with the 8.1 average draft position (ADP), the seventh highest such value amongst all players. Gronk's ADP in ESPN leagues is a more moderate - but still very high - 14.4, the fifteenth best.

It is in your best interest to pass on Gronkowski at those junctures in the draft. The most obvious reason is his injury history. While Gronk has consistently put up elite fantasy numbers when healthy, due to injury he did miss a combined fourteen games in the 2013 and 2014 seasons.

However, while the injuries are surely concerning, they should not drop Gronk more than a few spots in the rankings. Every player comes with question marks and most injuries are unpredictable. And while quarterback Tom Brady's likely suspension will curb Gronk's potential for the first four games, Gronk is a talented enough player to still thrive with a lesser QB.

The primary justification for dropping Gronk in the fantasy rankings has absolutely nothing to do with his expected performance. Rather it is the application of a very simple economic concept: opportunity cost.

For those of you who don't know what that is, opportunity cost is the value of the opportunity that one foregoes when they choose one option over another. In other words, it is what you are missing out on.

If you expend a late-first or early-second round pick on Gronk, or any tight end for that matter, you are missing out on the opportunity to take an elite running back or wide receiver. The inverse, however, is not true; that is, if you draft a running back or wide receiver with that selection, you are in no way precluded from securing a great tight end later on.

Let's take a look:

ESPN Tight End Average Draft Position

Yahoo Tight End Average Draft Position

As you can see, in either league, you can grab the second best tight end, Graham, with a late-twenty pick. A very solid tight end like Martellus Bennett should be available in the 60s. Heck, you could even wait until the very end of the draft and nab Gates. Sure, you will have to make due with another tight end for four weeks, but you would be getting three-quarters of a season's worth of a great tight end for next to nothing.

So how do these tight ends compare to the other players available at those spots? For each of the top ten tight ends by ADP for each site, I will take a look at the top running back and wide receiver available at that point. I'll also throw Gates in there for good measure, as he is likely going to be starting for his draftee's team eventually. Along with each player, I included their ADP positional rank.

ESPN

Yahoo

In either league, the opportunity cost of drafting Rob Gronkowski is an elite (top 10) running back or wide receiver. Unfortunately, this will likely leave you in a situation where you are starting running backs or wide receivers who you would rather have on your bench (such as Bernard or Jackson), and if your starters are on a bye week or injured, you may even have to start RBs or WRs whom you would rather not have on your team at all (such as Williams or Garcon).

Or you can take the alternative option. You can select a very good running back or dominant receiver instead of Gro nk, and still end up with a solid starting-caliber tight end falling into your lap much later on.

I'm not arguing that Rob Gronkowski is not a great fantasy tight end. I'm not even arguing that he is overvalued. However, at the very least, his tight end peers are being more undervalued than he is.

So while it may be tough to pass on having a guy that parties as hard as Gronk on your fantasy team, your team will likely look better because of it.