This is a good question re: the timing. I think it's a little bit of "all of the above." Timing seemed a little weird at the combine, especially with the WRs. I don't know if they changed something with the way they were doing the times on NFL Network, but it seemed like the slow times across the board the first few days of the combine might have something to do with the way they were doing the start. I also think it is fair to say that this year's WR class is slower than normal even without any changes in the combine measurements. There are fewer burners in the class.
As far as the 4.57 comment re: Thomas, I don't think there's a fine line like 4.57 is good and 4.60 is not. But I think you have to judge each player individually and a 4.57 isn't a bad time for Thomas. He's a legit 6'3, 210+ and plays big. He also timed well in the quickness drills. I think you wanted to see something in the 4.5s from him and that's what he did.
As for Carroo, I'm with you. I don't understand why he's getting so much hype. I saw that in rookie mock drafts he is currently going in the top 5 overall. That seems way too rich for me. I can see the case for him as a late-first rounder in what is a pretty weak draft class, but I'm not getting the top 5 love. I think part of why dynasty people like him is that there is this whole group of people doing prospect analysis that are very focused on the college stats and specifically "market share." I think it's a badly flawed metric that is going to automatically make receivers on bad teams look better than receivers on teams with good depth. Carroo is a perfect example. I cover college DFS for Footballguys and focus on the B1G so I know more about Rutgers WRs than is healthy. It's a very unimpressive group. So it's not surprising that Carroo (who is a legit Day 2 prospect) was better than his teammates and racked up a huge % of the passing yardage and touchdowns. Does that tell us anything other than that he's better than a bunch of bad college players?
To continue on the "market share" tangent, I think it's especially interesting to compare Michael Thomas and Carroo. Some of the analysts who like Carroo a lot more than Thomas point to the market share stuff, but that's such an apples-to-oranges comparison. On the OSU offense, you have a 1st round RB who catches passes (Ezekiel Elliott), a round 3 TE prospect (Nick Vannett), a pair of 2nd round WRs (Michael Thomas and Braxton Miller) and another late-round draftable player (Jalin Marshall). Of course the targets are going to be spread around between those 5 guys and nobody is going to have 40% of the yards. But put Thomas on Rutgers in place of Carroo and he'd dominate targets, yardage, touchdowns, etc. in the same way Carroo did because he'd be the only legit B1G WR talent on the roster.
I agree that "market share" measures favor receivers on certain sorts of teams. It's good for WRs who are the only good receiving option on their team, and bad for WRs who have lots of other good receiving options on their team.
That's why it's good to also look at other measures. Efficiency measures like yards per target favor WRs who have great teammates and a great offensive system. It's bad for receivers who are the only good receiving option on a bad team, because it's hard for a player to have high YPT when the defense can scheme to give him lots of extra attention (and when the QB is not so good at getting the ball to his receivers with accuracy & timing).
There are some systems (like Georgia Tech's run-heavy offense) which tend to inflate both the market share and the YPT for their top WR, so it's also good to look at totals: yards per game, TDs per game, 25+ receptions per game, etc. These totals will be somewhat inflated for WRs on pass-happy offenses and for WRs on good offenses, which is especially an issue for high-flying offenses like Baylor & Western Kentucky which hit both of these.
Carroo stands out as a prospect because he has very good numbers by all of these metrics. He has a huge market share, which is unusually big even for the go-to WR on a team without other good receiving options. His yards per target was one of the highest in college football, even though you'd expect guys in his situation (the go-to WR on a bad balanced offense) to struggle at YPT. Carroo also has good per-game totals (not as good as his market share or YPT, but still up there). So he has a really strong statistical profile in part because it looks good whichever way you look at it. Some comparisons:
Leonte Carroo: 101 Yd/g, 1.25 TD/g, 44% of Rec Yd, 59% of Rec TD, 13.8 YPT
Michael Thomas: 60 Yd/g, 0.69 TD/g, 32% of Rec Yd, 47% of Rec TD, 7.9 YPT
Josh Doctson: 121 Yd/g, 1.27 TD/g, 35% of Rec Yd, 42% of Rec TD, 11.4 YPT
Corey Coleman: 114 Yd/g, 1.67 TD/g, 39% of Rec Yd, 49% of Rec TD, 9.9 YPT
Laquon Treadwell: 89 Yd/g, 0.92 TD/g, 27% of Rec Yd, 32% of Rec TD, 8.4 YPT
Leonte Carroo 2014: 84 Yd/g, 0.77 TD/g, 37% of Rec Yd, 45% of Rec TD, 11.6 YPT
Would Michael Thomas's YPT have been a lot higher if he was on Rutgers, catching passes from Chris Laviano (in 2015) & Gary Nova (in 2014) instead of JT Barrett & Cardale Jones? Would Carroo's YPT have been a lot lower at Ohio State?
