It's true that most of the plays that make the top list are ones where the ballcarrier gets into the open field and is able to run mostly straight ahead for 20+ yards and get up to speed.
But top speed on these plays is correlated with having "good speed" in other ways. It's not F-Zero where the car with the fastest top speed has the slowest acceleration - generally players with fast top speeds also have fast acceleration. Players may not come close to their max speed on most plays, but it's relevant in the same way that the broad jump is: a good broad jump is a sign of good explosiveness, which matters on lots of plays even though no one ever does a standing long jump on the field.
Players only have a chance to get close to their top speed occasionally, but if a receiver got the ball 120 times then that's probably enough for him to have a few open field opportunities. And if he was unable to shake free to create an open field opportunity on any of those 120 touches then that is also a bad sign.
So not making these charts does seem like a bad sign about a player's speed. If a player just barely made the list once, with a 19.27mph as the 20th fastest speed of the week, then that is also a somewhat bad sign. But that mostly feels like a reason to also be worried about the WR who never did better than 20th, rather than a reason to not be worried about the guy who never made the top 20. Out of the 77 WRs with 80+ touches, these 12 never made the top 20 list and there are another 11 WRs only made the top 20 once and never topped 19.5mph. So maybe we should be flag those 11 guys too (Julian Edelman, Terrance Williams, Keenan Allen, Kenny Britt, Eli Rogers, Rishard Matthews, Tyler Boyd, Jamison Crowder, Jeremy Kerley, Deonte Thompson, Seth Roberts).
It's true that speed is only one component of an overall evaluation. I'm more concerned about guys like Alshon Jeffery and Dez Bryant than guys like Beasley, Amendola, and Edelman. Beasley is a slot guy whose job is to be shifty in tight spaces, so speed is less relevant for him. Whereas Jeffery used to be more of a prototypical WR1 - in 2013-15 he put up big numbers and got used all over the field as a deep threat, as a jump ball receiver, and as a weapon who the Bears would try to feed the ball to on plays like jet sweeps. But over the past 2 years his total production is down and he hasn't had a single rushing attempt. There's a question (which
we discussed a few weeks ago) of whether he just had a couple down years because of bad Bears QBs / adjusting to a new system and QB in Philly / playing through things like his shoulder injury, or if he's lost a step and is now mostly just a jump ball / contested catch receiver. The fact that he didn't make the top speeds lists points to him losing a step, and makes me inclined to agree with folks like
@FF Ninja &
@voiceofunreason that I had him ranked too high.
Next Gen Stats also
has data on receivers' average separation, "The distance (in yards) measured between a WR/TE and the nearest defender at the time of catch or incompletion." This is a mixed signal - getting targets with low separation is a sign that your QB trusts you enough to throw it up to you when you're covered and let you make a play on the ball - but it seems relevant to note that Jeffery also has the second lowest average separation over 2016-17 (min 80 targets). That also fits the story of Jeffery losing a step and having trouble getting separation.
Here is everyone with less than 2.3 yards of average separation (2016-17 combined), min 80 targets:
sep player
1.9 Kelvin Benjamin
2.0 Alshon Jeffery
2.1 Mike Evans
2.1 Marvin Jones
2.1 Dez Bryant
2.2 DeAndre Hopkins
2.2 Demaryius Thomas
2.3 Michael Crabtree
Four of the names overlap with the 11 players in the "never in the top 20 max speed" list: Benjamin, Jeffery, Bryant, and Crabtree.
Dez Bryant has a similar story to Jeffery's - huge production as a prototypical WR1 in 2012-14, becoming more of a contested catch artist of late, questions about how much of that is about adjusting to a new QB versus losing a step. The fact that he joins Jeffery in both the low separation and the low top speed list seems like a bad sign.
Crabtree is more of a possession receiver, and had a good season in 2016 despite his low top speed & separation that year. So this is less of a cause of concern for him, but I think it still matters some to see the combination of poor production in 2017, the Raiders deciding to move on and cut him, and low separation and low top speed in 2016-17. Kelvin Benjamin has a similar combination of low separation and low top speed, while his production wasn't great and his team decided to part ways, though again it's less concerning than Bryant or Jeffery given that he has a reputation as a big slow guy who wins with size.
Allen Robinson fell a bit short of the cutoff for number of touches, but it also seems worth noting that he also never reached the top speed list and would've been 3rd on the low separation list. Smaller sample size with him, and it was the Bortles-led 2016 Jaguars, but this makes me a little less optimistic about his chances of returning to his 2015 form in Chicago.