Torridjoe's Blog

Torridjoe

Feb 04

Blazers After Twenty: Does FG% Matter?

By Torridjoe

We’re about 20 games into this lockout-altered season, approaching one-third of the schedule completed.  And we’re at another of those natural breakpoints in the Blazers season after a mighty satisfying blowout of a suddenly hapless Phoenix Suns group. The Blazers “only” shot 47% against the Suns, and I put that in quotes because to a fan it certainly feels like a stellar effort from the notoriously streak-shooting home five of 2011-12. Indeed, it was Portland’s fourth best shooting game of the year, and reversed a rough patch during the 2-4 road trip and another quickie at Golden State, in which even two or three additional points could have made the difference in those games.

The primary critique of Portland surrounds backcourt shooting, which has been up and down–mostly down, way down like Tierra del Fuego. Wesley Matthews, Ray Felton and Jamal Crawford have all struggled mightily at different points to start the season. Legitimate excuses aside regarding the crazy schedule, the reality is what it is, and each of them has stunk up an arena or two so far. (They’ve also each lit up a couple, which is why they’re up AND down, yah?)

It feels like the team lives and dies by the (for them) somehow uncontrollable metric of whether the ball goes through the cylinder or bounces off. Shoot well and they win, otherwise forget it. That may not seem radical;  in fact it sounds like common sense, notwithstanding Portland’s recent-years ability to transcend their shooting with good rebounding, slow pace, FTs, and a variety of intangibles (not to mention clutch star play from Brandon Roy) despite laying bricks like a homebuilder chicken working overtime.

But is it true? Does field goal percentage have enough importance that it controls a compelling part of the outcome? Can we expect slow-starting teams with good FG% to bounce back, necessarily? Are lucky teams with low percentages doomed? Do the Blazers live and die by swish vs. clang?

What am I, Siri? I sure hope you don’t think I’m going to definitively answer a bunch of theoretical questions with 20 games of data from an anomalous season. I’d be nuts. But that doesn’t mean we can’t take a look and see if there’s any data support to the idea that FG% has a lot to do with wins this year, particularly as it concerns the Blazers.

The quickest way to answer the question is to take all 580 games played through Sunday (which actually is a pretty decent sample, leaguewide) and compare FG% in both wins and losses. The tale of the tape on that score is that losing teams shoot 41.6%, winning teams 47.1%. Aha! Over five percentage points different! There IS something to it! Well, yes and no. There’s some kind of variance, obviously, and it follows common sense: more shots in means more points, more points means better chance to win games.

But because I compared those two means using a test called a two-tailed T-test, I also checked whether the difference had any statistical relevance–or whether it was akin to random chance. That relevance is reflected in a p-value, and it is only worth your time if it’s .05 or less–or in English, about 95% sure you’re right and it’s not random. The p-value on this one? 2.3. So forget what you thought; percentage of shots made doesn’t predict who wins, at least not so far this year–in this year of chaos, you may well expect the chaos theory of data to prevail.

So we’re starting from the premise that you can conceivably be a crappy shooting team and win consistently. But does it matter more to some teams than to others? That’s why we got here; I wanted to see if the Blazers live and die by the arc and fall. For that, I got a little fancier than comparing means. Portland has 20 games in the books and sits at 12-8, currently good for 7th in the West. They are 9-1 at home, 3-7 on the road. To look at whether any teams rely heavily on FG%, I did a Pearson’s correlation (no idea who Pearson was, pretty sure you don’t care and I know I don’t) that gives you a number between -1 and 1. The closer you are to the extremes, the more tightly the two are related.

To explain a bit, if after correlating FG% and Wins by applying a formula I have long since forgotten and used Google spreadsheets to calculate, you find a relationship that is perfectly correlated–as one goes up, the other goes up, every time–that’s a score of 1. If the relationship is perfectly inverse–as one goes up the chance of the other goes down–then it would be -1. If you get 0, you have random data chaos. This relationship is generally expressed as R2 or r-squared. Anything below -.5 or above .5 is meaningful–subject once again to a test for significance. I’ll spoil the suspense–at the league level, the R2 is .46, so not related. But for the record, here are the variations by team:

0.72 ORL
0.68 MEM
0.66 DAL
0.63 UTA
0.62 ATL
0.58 DET
0.57 MIA
0.55 CLE
0.53 POR
0.53 BOS
0.52 NYK

——Line of Relevance–

0.49 CHA
0.49 TOR
0.49 IND
0.45 LAL
0.44 MIL
0.41 WAS
0.38 NOH
0.34 PHI
0.33 DEN
0.33 NJN
0.32 CHI
0.32 SAS
0.31 LAC
0.30 OKC
0.29 HOU
0.25 MIN
0.17 PHO
0.06 GSW
-0.04 SAC

That’s quite a range, including one team–the Kings–that is almost entirely random but if anything leans towards doing better the worse they shoot. OKC and CHI both appear on the more random side, as do Philadelphia and Denver, suggesting that something else is driving the train for them because they’re winning pretty much regardless of how well they shoot that night. Maybe it’s because they almost always shoot great; Denver, OKC and Philly are 2, 3 and 4 in overall FG%, and the Bulls are 7th. But here are the Spurs and Warriors at 5th and 6th in FG%, and that’s apparently not impacting their win total at all–atrocious defense being another potential factor in those cases. I think the top teams don’t necessarily need to shoot well, but often do anyway. Miami is torching the nets at 48.6% so far, but even at that elevated average, if you believe their R2 you can beat them if you catch them on an off shooting night.

The Blazers are just above the line at .53, so the best short answer is “certainly possible” that FG% matters to their record. What is true is that every time Portland has shot over 43.1%, they have won. Well, actually they’re 9-1, the lone exception being ironically their 3rd-best shooting night vs the even hotter Orlando Magic at the Rose Garden (who posted the 7th-highest FG% in the NBA so far this year at 58.6%, not to mention an amazing 59% from 3PT, in 27 attempts!). Of those 10 games, all but two were at home, and those two high-shooting road games were both wins (@OKC, @NOH).

Below the 43.1% threshhold, the Blazers are 3-7 and only one of the three was a road win, vs a terrifically anemic Toronto team that you can outshoot with a wet cap gun. Shooting less than 43% ought to doom you in the NBA unless you put 48 minutes of hell on the opposing offense, which the Blazers do not. Another win was vs Cleveland, no surprise there–but the third was an early contest at home against Philadelphia, in which the Blazers hit nine three pointers and 17 of 23 foul shots to snare what has become a rare win from the 76ers.

So if you’d like to take this as some kind of vague validation for the idea that the Blazers prosper and wither by their floor accuracy, be my cautionary guest: yeah, maybe there’s a connection there. You could also say they win when they score 100, but they’ve also won four times under 100, and that’s a much more pace-dependent kind of stat. You can bet unless the other team is shooting the lights out, however, that the Blazers should come away with a win if they can even muster something better than 4 in 10 from the field. Watch for it the rest of the year and see if that continues to be the rule.

1 Comments

  1. field goal percent does matter. i tweeted Mike Rice before the sacramento game and asked what it would take for us to win. his response: shoot at least 46 percent. we have a good defensive time for the most part, but we need to increase the offensive output. i'm going to put that one on the guards. we need these guys to start consistently knocking down some shots. we do that and we'll climb the ladder in the west.

    ~ KMM

    by Kassandra on 2/6/2012 4:10 PM
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