Xavier Woods is right, you know?

The relationship between Woods and Cowboys fans never recovered as the team continued to falter. Dallas let him walk, opting instead for Damontae Kazee — with Jayron Kearse filling in while Kazee gets healthy. Now, Woods has signed a one-year, $1.75 million contract with the Minnesota Vikings. He will be the de facto starting safety — draft miracles notwithstanding — and that effort problem is now our problem.

Should we be concerned?

The optics on that quote are not encouraging, but Woods does have a point. Players don’t take it easy on some plays because of laziness; it’s a point of strategy. After accounting for stoppages and downtime, there are about 11 minutes of full-speed gameplay in a typical NFL game. For cornerbacks and receivers, that means about 1.25 miles of total distance covered. Over 70 plays, that averages to about 31 yards covered per play. Safeties run a little less, but the idea remains.

Even the most honed and conditioned athletes will lose a step by play 65 or 66 if they sprint all 31 yards on each play. It stands to reason that a player would slow down as the game wears on. Big Data Bowl contestants Cathy Ha and Lucas Calestini investigated this in 2014 but found the opposite. Depending on position, players don’t slow down that much over the course of a game.



Players likely don’t want to play at their slowest during the fourth quarter, when stakes are highest. So conserving energy for that moment is paramount. The above graph suggests that players are pretty good at conserving energy throughout a game. At safety specifically, there is ample opportunity to find some rest without jeopardizing your teammates or the result of a play.

Here’s every snap from the first quarter of Minnesota’s 2017 shutout at Lambeau Field, focused in on Harrison Smith. This game won him NFC Defensive Player of the Week honors, but watch how often he plays at a light jog.

When you lift weights, trainers recommend that you lift in sets and take breaks in between those sets. ATP gets used up pretty quickly and has to replenish. A well-trained body — like an NFL athlete’s — can replenish that ATP but needs a bunch of oxygen to do so. Hence, “catching your breath.”

You don’t necessarily need to know all that to understand that a player won’t want to be winded as they head into a key play. So if the opportunity presents itself to lightly jog and stay alert, players should take advantage. It’s not a lazy way to play, it’s a strategic one. The key skill is choosing the correct plays. You’ll notice that Smith won’t sprint across the field to chase down a toss to the other sideline. That’d be a fruitless waste of energy. However, he will play hard in coverage or in his run fits.

When Woods talked about effort, it sounded like there were some legitimate issues in Dallas. Mike Nolan was fired after the end of the season, which is no coincidence. That defense struggled. But Woods is right when he says it’s impossible to go 100 percent for all 70 plays. Maybe it should remain unsaid, but with a little understanding of how the human body works, we can also understand why players need to jump on opportunities to restock their ATP stores.