On Tuesday morning, Outside the Lines released a damning investigation into the link between Spygate and Deflategate, two scandals that have consumed the New England Patriots in the past decade. There were a lot of revelations in there, but one of the more damaging ones had nothing to do with taped signals or the Ideal Gas Law. From Don Van Natta Jr. and Seth Wickersham’s report:
Several [former New England coaches and employees] acknowledge that during pregame warm-ups, a low-level Patriots employee would sneak into the visiting locker room and steal the play sheet, listing the first 20 or so scripted calls for the opposing team’s offense. (The practice became so notorious that some coaches put out fake play sheets for the Patriots to swipe.)
In response, Yahoo’s Charles Robinson wrote, “Knowing the first 15 or 20 offensive plays scripted by an NFL team is knowing the future.” If the Patriots indeed stole scripted play sheets, we’d expect to see their defensive performance peak early in the game, only to wilt later on. Indeed, the OTL report gives evidence of games where New England’s defense was staunch early, but later gave up big yardage.
But that’s anecdotal evidence. There’s a more empirical way to judge whether or not the alleged play stealing had any effect.
The chart below compares New England’s defensive performance for the first 5 playsof the game (when the Patriots would have had knowledge of what was coming) with the second 5 plays of the game (when they wouldn’t). (I also contrasted the first 20 plays and the second 20 plays. The results were similar). If New England was stealing play sheets, it would, in theory, yield fewer yards a play on the first five plays of the game than on the second five plays of the game. Armchair Analysis provided the data.
Interestingly, the shapes (histograms) are very similar, both within each era and in terms of the difference between eras. Further, in pretty much every year (not shown), there’s a consistent overlap between the yardage New England allowed on plays likely to have been scripted and those less likely to be scripted. Finally, in terms of average yards per play, New England’s patterns tend to match numbers from the rest of the league.
What’s the take home? It could be a couple of things. One explanation is that New England stole a bunch of play sheets, but just did a poor job of using them. Alternatively, as suggested in the ESPN piece, rogue opponents could have subbed in fake play sheets, fooling the Patriots and potentially our numbers. Of course, one or two stolen sheets probably wouldn’t show up in our data, and because we have no idea exactly which (if any) sheets were stolen, it’s somewhat hard to define what we are looking for.
Interestingly, the more noticeable change is that the Pats defense gave up about half a yard more per play overall post-2007 than pre-2007. Of course, there are several explanations for such a drop in performance, including differences in team personnel beginning and/or league-wide changes in offensive strategy. Conspiracy theorists, however, could argue that with a unit no longer able to accurately predict play calls, the Pats’ defense suffered. But this seems like a bit of a stretch. League-wide, there was no difference post 2007.
Finally, although its tempting to jump to aggressive conclusions, it’s a good reminder that an absence of evidence is not evidence of an absence. Instead, all we know is what the data tells us, which in this case, is only a small part of the story; on a yards-per-play basis, the Pats defense was pretty consistent before and after an opponent would script its plays.