NBA Finals 2017: Why the Warriors’ Game 1 shooting percentages shouldn’t be a concern

Richard Jefferson seems to believe that the Warriors 42% shooting in Game 1 is an encouraging sign for the Cavs, but that single number doesn't tell the full story.

There was some light chatter on Twitter yesterday about Richard Jefferson observing that the Golden State Warriors only shot 42% in their 113-91 win in Game 1 of the NBA Finals.

To summarize, Jefferson’s argument is this: if the Cavs were able to hold the Warriors to 42% shooting, they don’t really need to make many adjustments because they’re not really that “far off”.

There’s some logic in Jefferson’s reasoning there: on the surface, holding the mighty Warriors to just 42% shooting seems like a sign that the Cavs could rest assured that their defensive scheme was sound and required no adjustments.

However, it’s not quite that simple. And that sort of simplistic read of statistics has a way of really annoying me.

First, as Jefferson alluded to, you simply cannot count on Klay Thompson shooting 3-for-16 from the field, even if he has been in one of those standard slumps of his throughout the playoffs. You also probably shouldn’t count on the Warriors shooting 42% on uncontested jumpers either.

Betting on the Warriors shooting that poorly again without changing a thing is putting faith in random variance and, unfortunately (for the Cavs), hope is not a plan.

Yet there are more reasons to rest assured that the Warriors are not facing a potential crisis after one game in the Finals.

The Warriors shot 46% through three quarters

Beyond the matter of luck, what I was immediately curious about was whether part of this was just a garbage time effect: the Warriors were already up 21 entering the fourth quarter so the outcome probably wasn’t in doubt for either team for the last period. Curry only played three minutes and the Warriors spread the minutes around to the whole roster. During a quarter in which nobody really seemed to care that much about changing the margin of victory, you can expect shooting percentages to drop. In fact, my highlight of the quarter had to be the moment when Matt Barnes busted this contested three in James Jones’ eye for the 113th point.

As it turns out, neither team shot well in that final quarter: both shot under 30 percent from the field. You are free to include that fourth quarter in your analysis of Game 1 (the ultimate hot take might have a headline like, “The blueprint for beating the Warriors lies in Cavs’ fourth quarter defense”), but I’m choosing to ignore that and will look at the previous three quarters instead.

The Warriors shot 46.30% during the first three quarters while the Cavs shot 36.80%. For reference, the difference between 46.30% and 42% is the difference between a slightly above average team and a team in dead last during the regular season. So yes, maybe there’s something to the idea that the Cavs can consider rendering a historically elite shooting team somewhat average...but you still might not want to walk into the game thinking adjustments are unnecessary.

How important is field goal percentage anyway?

Field goal percentage does matter in a game predicated on making field goals for points, but there are probably more useful statistics.

One more useful way of looking at shooting percentages is effective field goal percentage, which incorporates the additional value of 3-point shooting into field goal percentage — since “3>2”, making threes probably should get some additional weight. And, for whatever it's worth to you, effective field goal percentage has a higher correlation to winning in part because making threes has a higher correlation.

So the following table holds the effective field goal percentage splits for both teams in Game 1.

Again, you’re looking at the difference between a well above average shooting team and a terrible one. We didn't get much from that other than satisfying my thirst for a stronger metric than FG%.

But what the tabular form does put in perspective is the real problem for the Cavs: the field goal percentage differential.

#h3 It’s hard to beat a team that out shoots you #h3

If you want to stick to basic basketball stats and find something in the box score that gives you a clear picture of what contributed to winning, you should look no further than field goal percentage differential. It requires no special knowledge to calculate and gives you a really good basis from which to start an analysis of a game.

A fairly comprehensive analysis of NBA stats on the Life is Study blog found, “Shooting percentage differential shows the strongest correlation to wins of any variable other than margin of victory. If you shoot a better percentage than your opponents more often than not, you are probably going to win a lot of games.” This is pretty much recycled wisdom from Dean Oliver’s Basketball on Paper and countless other studies. But it underscores why I found Jefferson's claim rather pointless: aside from the fact that I felt Game 1 FG% was misleading, if the Warriors had a field goal percentage 10% higher than that of the Cavs (or an eFG% 7% higher) then the Cavs have problems. And following the wisdom of Oliver’s Four Factors work, that's what makes Tristan Thompson's “trash” performance on the boards all the more significant: if you're going to get outshot, you absolutely have to win the other three categories of Four Factors. The fact that Tristan Thompson was so ineffective on the offenisve boards was huge in light of the Cavs’ shooting struggles — Tim Kawakami of the Bay Area News Group got Thompson's thoughts on that and I think Athletic Alchemy’s video breakdown of the game did an excellent job highlighting that problem (h/t BornInDaEB for the FanShot). You can't miss shots, not recover offensive rebounds and turn the ball over more often than your opponent and expect to win games.

Maybe in Jefferson’s eyes the poor shooting, turnovers, and rebounding were all flukes that don't need adjusting so much as a second chance. But again, it seems like that's relying on hope instead of deliberately planning to do something different.