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Hello! This thread is awesome. Let's have some home truths about spotting the ball that may be of interest. In the normal course of events, there are three acceptable ways to spot the ball. "Nose on", with its front end on a yard line. "Tail on", with its back end on a yard line. And "Middle", where it's halfway between two yard-lines. Covering officials are also encouraged to make the spot nose on where possible after a first down, and it's always done after a change of possession. (This avoids wasting time with measurements; if we started nose on the 23 and we're now nose on the 33 it must be a first down.) This is drilled into you so hard that you never give a spot with the middle of the ball over a yard line. You just don't see them; in the time it takes to see the runner go down and decide where the football was, they always look like tail on or nose on spots. Related to that. This? Totally not accurate. quote:This can yield some funny outcomes – for instance, if a team throws an incomplete pass on a 4th down, and the line of scrimmage is between the opponent’s 15th and 16th yard markers, the official field position is “opp 15” on the 4th down, but then flips around to “own 16” after the other team gains possession, despite the fact that the actual position of the ball never changed. If you watched the Umpire carefully, I would bet an extremely large amount of money that the new ball gets spotted nose on the 16. Need nose on the 14 for a new first down, and the spot after 4th down is nose on the 15? Watch the Umpire carefully, and again I have a large amount of money saying that he will then pick the ball up after everyone sees it's a yard short, give it a nice good clean off, and then put it back down the other side of the 15 so it's nose on again. Of course if you're in a college game or something where each team is allowed to use their own footballs, that's when the spot adjusts itself. The one time in a million when someone actually notices and might possibly kick up a fuss? "Whoops, senior moment." Move it back, but the Head Linesman's almost certainly not going to waste his time resetting the chain for that one time in a million. The exception to this is at the line to gain. Within a yard of the line to gain you must give an exact spot, regardless of where that means putting the ball down. If you don't realise you're at the line to gain before the runner's fallen over, occasionally you get this very Zen little moment as you re-adjust the reality of what you've just seen from "yeah, that's a tail on spot" to "actually, thinking about it, the ball was exactly there". We're not talking about an adjustment of more than six inches or so, mind you. It's possible that this might have something to do with the divot on X-yard runs, where X is the number of yards you need for a first down (since it will certainly lead to a few spots that would have been "meh, close enough for nose on" being given a few inches short instead), but I'm more inclined to believe in the scorekeeper effect. How many of these close spots are there in a game? Maybe two or three? There's certainly quite a few games that go without a single measurement. I'd be willing to bet that they're far too few to be statistically relevant. And then, some of those hypersensitive spots are going to end up as a first down in a place where the scorekeeper goes "that's still on the 30" and makes it an X-yard run. So here's what I'd like to be sure about. 1st and 10, nose on the 20 going out. First play is a run that ends tail on the 23. Does the scorer think this is a 3-yard run to the 23, or does he round it forward and make it a 4-yard run to the 24 (even though the ball is still physically touching the 23)? It sounds like they should round it forward, since there's less than 7 yards to the line to gain. And long as I understand the NFL guidelines properly, it then becomes extremely difficult to make a run that gets recorded as X yards. Again, the line to gain is nose on the 30. Any spot from tail on the 28 to a blade of grass short of the 30 is, statistically, going to result in a run of X-1 yards. That's a double-sized area of ground for the ball to end up in and be recorded as an X-1 run. And then it's being squeezed the same way the other side of the line to gain. The only way you're getting an X-yard run here is to get it nose on, because of course, as soon as you go to tail on the 30, then just like at any other time, they round towards Team B's goal line again and make it an X+1 yard run. Now consider that as soon as the ball crosses the line to gain, the official is going to make the next spot nose on; that also increases the chance of an X+1 yard run, because some spots that would be given as tail on the 31 or middle 31-32 are going to get adjusted back to nose on the 31 and change an X+2 yard run into an X+1 run. I reckon that's going to happen far more than X-yard runs get moved a few inches back. Here's the other side of the divot for you. Is there perhaps a similar bump of Y-1 gains, where Y is the yards required to score a touchdown? Any spot from tail on the 2 to a blade short of the goal line could be recorded as a Y-1 run to the 1-yard line, unless they've got another special rule to cover that. Incidentally, I did find it interesting that the NFL stat rules try as hard as possible to avoid half yards, since an old-time Texas high school official once told me that you start a new series nose on because the stat guy hates having his nice clean stats being mucked up by e.g. a touchdown drive of exactly 65.5 yards. (You keep the stat guy sweet because then he'll save you when your crew splits 3/2 on "wait, what down is it?") Wonder if they still do half yards somewhere else.
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Mar 18, 2016 00:41
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Forever_Peace posted:Wow, very cool info! You sound like a ref of college/high school ball? I call very very very bad football in another country; the best games I've done have been about equivalent to NAIA or NCAA Div III. We do bring over NFL and senior Div I-A officials to deliver training sessions, and they're who we learned nose/middle/tail spotting from. quote:So to clarify, the "opp 15" (for a ball at the 15.5) does become "own 16" after a turn over on downs, but the ball actually does move because the officiating crew pushes it to nose-on the 16? Yes. If you want a time to look out for it that'll show up on a TV broadcast, try watching for downed punts, and compare where they get downed to where the ball is then lying before the center puts his hand on it. (You can't necessarily trust it when you only see the center with his hand on the ball, because he may have significantly adjusted it on the ground.) quote:In any case, both the official rules and various manuals of football officiating I've checked suggest that officials should make exact spots Of course they do. The rules are the rules, and American mechanics manuals quite sensibly don't write down things that might be unhelpful if the media or a grudge-bearing idiot coach got hold of them. quote:With the higher scrutiny of the NFL, I do wonder how much the unofficial rules of rounded spotting (vs. the official rules of exact spotting) hold sway. I was under the impression that exact spotting is usually the goal. Two things you can look for when you watch your buffer. If all spots were expected to be given exactly, there would be a noticeable proportion of spots during a game where the middle of the ball was on a yard line. There would also be a number of spots during every game where the ball would be between two yard lines (what we call a "middle" spot), but it would not be exactly between the two lines; it'd be biased a couple of inches towards one line or the other without quite touching it. However, pay attention to where that ball is before the center touches it, and you'll see that it never goes down spanning a line, and when it's a middle spot it's always exactly halfway between the two lines. That's not credible if the covering officials are trying to give exact spots on every down. (This all assumes that the ball is not within a yard of where the line to gain is, or was on the last down; that's when you'll see the odd exception.) quote:The NFL guide to statisticians specifies that when any part of the ball is touching a yardage marker, the field position (and thus gains) are calculated using that yardage. So nose-on 20 is interpreted as own 20 and tail-on 23 is interpreted as own 23, for a 3 yard run. If the ball was spotted even a few inches further forward, such that no part of the ball is touching a line, it would be rounded forwards to own 24, for a 4 yard run. OK, so that narrows the zone in which you can make an X-1 yard run, but it's still much bigger than the zone in which you'll get an X-yard run, which is limited to nose on/tail on the line to gain, and tail on the line to gain will happen a lot less than it might because a lot of those spots will turn into nose on again. There's probably an added layer of granularity you can go into by looking at what happens when you have e.g. 2nd and 5 with a nose-on spot compared to 2nd and 5 with middle and 2nd and 5 with tail on (for extra credit, see if you can detect a difference when the line to gain is a main 5-yard line, or when the series didn't start nose on), but trying to work out the exact details of how it might affect things make my brain hurt.
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Mar 18, 2016 15:58
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That sure does look like good honest statistical analysis and not like anything else at all 
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Feb 14, 2017 14:39
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