It's similar to the comments echoed about a non-catch against the Steelers from the year before. Granted in this instance, I was significantly off the mark about how far he was from the boundary; I couldn't find a replay prior to making my initial comment, spit-balled it from memory, and was underestimated the distance. That said, in reviewing the play, the notion that the reception wasn't just feasible but was also expected appears to either gloss over the inner workings of movement and momentum or disregard them entirely. Going through the breakdown, conceptually speaking, the play call and the initial execution were essentially perfect.
We line up in a trips right, with Ben Watson technically as the inside slot WR, Breshad Perriman as the outside slot WR, and Mike Wallace as the Z on the outside. Michael Campanaro is the X receiver on the opposite side, and Jeremy Maclin is technically at RB (
Link). The Steelers deploy a Cover 3 from their base 3-4 defense with off-coverage on the outside, and we counter with a flood concept route combination that was a Cover 3 killer. Wallace runs a fade toward the back of the end zone to occupy Joe Haden, who is covering that respective third. Ben Watson runs a 5 yard hitch, drawing Vince Williams, who's covering the hook zone. Camapanaro immediately looks back and shuffles his way forward signifying his designation as a space-eater; he's covered by T.J. Watt in the flat route with Arnie Burns standing idly overhead. Here's where the development gets interesting. Maclin runs a flat route with Perriman running the out-and-up. Bud Dupree initially sticks to Perriman, who head-fakes the out route, compelling Dupree to crash down on the open Maclin. Dupree does this because the entire shell is rolled to the trips side prior to the play, and Sean Davis is intended to cover the curl zone where Perriman is running his route; however, he's duped by the head-fake and doubles on Watson's hitch route, allowing Perriman to cut upfield and sprint at an angle favoring the pylon. The ball is thrown as Perriman is sprinting forward, which is thrown towards short towards his outside shoulder, and there lies the problem.
He's on the last stage of the out-and-up, meaning he will innately look for the ball by turning to his inside shoulder. His momentum is carrying him upfield angled towards the sideline in the direction that he's sprinting. In order to adjust for the throw, he's limited to an immediate two-step process of having to slow his momentum with just his trailing leg while beginning the shuffle, and attempting to leap and drastically change direction using only his lead leg, which is moving upfield, to generate enough torque to adjust for a throw that requires both a 270° turn and a jump angled in that same direction prior to the turn. For those playing at home, that's when you can wipe away your scoreboard. Realistically speaking, that goes from improbable to borderline impossible. Jordy Nelson had a similar situation in 2011 wherein he came down with the ridiculous grab, and even in his scenario, it was a much more expected back-shoulder throw on an upright vertical fade and he had enough time to slow his momentum with both his trailing and leading legs, switch to a shuffle, and then launch himself afterwards with both legs to propel himself into the direction of the throw. And that reception was so mind-blowing, it was featured on SportsScience, and it remains memorable a half-decade later. Personally, I was almost surprised that it even touched Perriman's left hand when it happened live. I've been as disappointed as anyone with the underwhelming performance to begin the year, but the suggestions of this being a routine grab portrays an almost disheartening disregard for how our bodies are able to move and operate. Even if you're sticking to that contentious notion, Perriman was free of any defender by a literal radius of 6 yards. It's hard to argue that making that throw is more difficult than making that catch, so the general focus seems to be partially displaced.