Football might be evolving, but fantasy football really hasn't. And that means that we can't overreact to the new paradigm in the NFL. Tight ends are catching more passes, yeah, but are they really consistently worthwhile fantasy assets?
In standard scoring leagues, running backs offer better points-per-games, but what about floors and ceilings? Well, consistent with my conclusions before, the top 10 running backs offer better floors and ceilings in half-PPR leagues, and it's the same in standard leagues. Also, tight ends are very top heavy, of course, and that makes having an elite guy (aka Gronkowski) worthwhile -- provided you don't have to start sub-par running backs or receivers as a result of investing heavily in the position.
Half-PPR settings, on which most of my discourse centered, is where things begin to look a little in favor of the receiver position, as averages are up and look better than running backs in the back half of the top-10, but if you recall, the floors and ceilings aren't necessarily in favor of receivers over running backs at the top of the position. Once the running back production drops off, receivers look to be about as viable, but you have to keep in mind
Again, based on averages, it looks like receivers are better for your team, but you have to keep in mind that investing early in wideouts might leave your backs lacking (based on bust rates). Also, running back has a more drastic drop-off than the gradual one at receiver, and elite backs don't just sprout up out of the ground. That's especially true when looking at floors and ceilings.
Ultimately, quarterbacks and tight ends are replaceable. A significant number of wideouts are producing solid numbers, but the elite crop of running backs are very valuable in standard and half-PPR leagues. You can justify the wide receiver approach in PPR leagues quite easily, but that doesn't solve the problem of finding consistent running backs.