In the last post I broke down WR prospect measurements going back to the 2008 draft. I focused on WR because it was easy for me to explain a specific position and come away with insights into what to look for when drafting that position.
Below I just want to point out other instances that stood out to me over the different positions with speculative insights I've gathered.
Positions where a faster 40 yard sprint time was more associated with a better "Career Value per Year" (again as determined by PFF):
With this insight you should think of in similar terms to baseball statistician's informative metric WAR (wins above replacement) in that with positions of higher correlations (value closer to -1), prospects who are faster than the average prospect will do 'more better' (yes I just used that, I thought it was an apt descriptor) than a faster prospects of other lower correlated (value closer to 0) positions. So a faster fullback (FB) prospect in the 40 yard sprint will typically provide more value to your team compared to his peers than a faster quarterback (QB) prospect versus his peers. This of course only considers the 40 yard sprint time measurement as an indicator; it isn't saying you should draft a fast FB over a fast QB when everything else is also considered.
One observation I'd like to make is that I found it interesting that a faster prospect matters more for the positions that line up closer to the "inside" of a formation. What this is talking about isn't who is closer to the ball in normal football terms of yards away (as in a DT is closer than a LB who is closer than a FS), but it is referring to who is closer to the middle of formation if it were divided in a vertical manner (as in a DT is closer to the middle than a DE, a LB is closer than a CB, etc.). I'm going to guess that this is because speed is more important to a position in the middle of the formation than at the outside because many times the ball starts in the middle and a play is run to the outside, so the faster a DT or middle LB is getting to the outside on a quick throw to the WR, the better. When the RB gets a carry and there is no hole to run through between his linemen, a faster RB that can break it to the outside is better than a slower one whereas a faster WR is already on the outside so his speed is less important to his position.
Where the data doesn't fit this theory is the safety position. Not only does SS have the lowest correlation among positions where a faster 40 yard time indicates a better player (meaning a faster player isn't that much better than an average one), but the FS position actually shows that a slower prospect is better than an average prospect. This could be due to the small sample size or one outlier that is very good and also slow, but success at the safety position seems to be the least dependent on speed of the position groups analyzed.
Positions where it is better to be 'quick' than 'fast':
Similar to how in my comparison in the last post I mentioned it was better for WR to be 'quick' than 'fast' (meaning there's a stronger association with 10 yard sprint times and better NFL career value per year than with 40 yard sprint times), I also did the breakdown per position. In the right most column you'll find the better attribute which was derived from taking the difference in the correlations. From this, it is better to be 'quick' than 'fast' for WR, DE and FS.
Positions where it is better to simply be taller or heavier:
Here the correlations per position are ordered by where it helps the most to be taller than average. Again the safety position is perplexing since it is better to be taller for a strong safety but better to be shorter for a free safety, but I think it's once again because of the small sample size.
Here the correlations per position are ordered by where it helps the most to be heavier than average.
From these two considerations alone, it is better to draft DE and SS that are bigger, as both height and weight are positive indicators of better NFL performance.
Positions where it is better to be able to jump higher:
Again safety continues to be such a weird position, I should have the best idea out of any of them since it's the position I played professionally... well if your profession is high school student. Oh well, basically it is better to be able to jump higher in the NFL, except if your job is to run the ball, in which case you want to stay as low to the ground as possible.
I could honestly continue and do an entire project on observations based solely of physical measurements. I think it's important to know what characteristics are good indicators of success at each position because the NFL is a copycat league and they want to draft players that fit these stereotypes. So a prospect that is stereotyped to be able to physically perform well in the NFL will typically be drafted higher than a player that is not often associated with success based on his measurements. I encourage others to take this premise (comparing PFF-style grades per year to physical attributes) and expand on it. Get undrafted player info, prospects prior to 2008 or make new, more descriptive metrics and improve on this analysis, I'm sure it will be useful to people that make decisions based on this information. You can never go wrong with more, relevant data. I'll help by posting my data after I turn in this current draft prediction project.