Jeff Thomas was faster than any of them coming out of high school, well at least the Class of 2016. Thomas has a chance to help himself at the combine if he runs back to that 4.38 prep level. But strangely he seemed to tail off as a collegian not only in terms of production but also raw speed and short area quickness and elusiveness. I'll be interested to see if any of that returns once his pro future is at stake.
I posted that link a couple of months ago with the finding that speed is overrated for wide receivers but underrated for running backs. However the league still doesn't see it that way so the 4.4 receivers with no competitiveness whatsoever will continue to be pushed up the ranks while the sub 4.5 running backs will drop to bargain range.
Regarding your point about the TCU quarterbacking...absolutely. It should be next to impossible to manage only 6.2 YPA in the Big 12. Prior to TCU this season, only Kansas had been anywhere near that level or below in the past 5 seasons.
I think the NFL rightly sees the value in WR's who stress defenses with their speed and wrongly pushes up bad WR's who are fast. If a WR is really fast but doesn't track the ball well, he's not really a deep threat, and he'll be relegated to a gadget role.
WR is one of the more skill-dependent positions on the field. Elite physical traits are still desirable, but WR is not a position where you can take a raw athlete and expect him to develop. Also, a lot of the speed guys are too slight, and the bust rate on slight WR's is very high.
The big point - to me - is that good WR's, who are also very fast, add a unique dimension to an offense and stress defenses in ways that good WR's, who are not fast, do not. Stretching the defense vertically is the biggest advantage and the one we usually think about, but with the increase in jet sweeps and motion in general, they can also stretch the defense horizontally. KC scored two TD's vs Tennessee on jet-motion plays with Hill - once where they gave him the ball and once where they used the motion to freeze the LB's. So, I don't think speed will make a given WR more likely to succeed, but I do think it has a big impact on the type of success that player will have in the NFL.