I like PORPAG. A lot. It's elegant. It's the only time something created by Spartys will ever be called elegant. I'm a sucker for a number that's simple to understand, simple to calculate, and remarkably informative. As you might remember, though, PORPAG ignores defense. It's strictly an offensive metric. I was thinking that I wished it did, so I set out to figure out if there were a good way to incorporate defense. The result is Enhanced PORPAG.
The new number I wanted had to also reflect "points above replacement" in the same way PORPAG does, because this was to be an add-on. No need to recreate the wheel: my goal was to stand on the shoulders of geniuses, to borrow a phrase. The problem, of course, is that there's no defensive rating the same way there's an offensive rating; if there were, someone would already have done this. You can't have a defensive rating the same as an offensive rating, though, because not every defensive possession is ended by the actions of a defensive player.
But some are. I'll spare you the list of discarded ideas and jump right into the equation, with explanations to follow:
EPORPAG = PORPAG * ( ( ( Block% / 2 ) + Steal% ) - 2.45 )
If PORPAG is negative, divide rather than multiply.
Explanation (if this is likely to bore you, just skip to the bottom where the CHART is):
A block or a steal are the two tools a defensive player has at his disposal to actively end a defensive possession. Rebounds are excluded because those aren't under direct control of the defender. That's just grabbing a loose ball - the fact that the shooter missed is almost never the result of the rebounder's actions. There's also the side effect that including rebounds would skew the stat inexorably towards big men. But blocks and steals are about even between the two, and again, that's how the defense can end a possession.
It's reasonable to assume that a steal denies the opposition two points, because the average possession that results in points, results in two. One point and three are about equally common. And a steal always ends a possession, whereas a block ends a possession roughly half the time.
So, add a player's steal percentage to half his block percentage to get the percentage of possessions he ends while he's on the floor. PORPAG multiplies O-rating to account for the amount of time a player is playing; block% and steal% already do that. It's built in. 2.45 is the "replacement level", obtained by:
1) Taking the D-I team average for each; 2) dividing each by five to represent one player; 3) multiplying by 0.87, because that's the proportion of replacement-level O-rating to the national average.
Example calculation: Zack Novak's PORPAG is 2.34.
2.34 * (((0.5 / 2) + 1.0) - 2.45) = 1.19. Novak's defensive numbers are well below replacement-level.
I already did this for the ACC on my own UVA blog, and it sanity-checked very well. There are a couple caveats, of course:
- It's kinda fishy the closer you get to zero PORPAG. A replacement-level offensive player could block literally every shot and still be replacement-level.
- It still doesn't account for unaccountable things like off-ball defense or chemistry.
I'm sure people can think of other things. But enough babbling. IT'S TIME FOR THE CHART.
|Year||Player||Team||PORPAG||Block %||Steal %||EPORPAG|
|Jr.||Ralph Sampson III||Minn.||1.73||8.5||1.2||3.84|
Some interesting, names, yes? Again, though, I think it passes the sanity test. The better teams are also generally the better-represented teams. Guys that contribute mostly only on offense get a bump in favor of more well-rounded players. I know, for example, that I looked at the PORPAG list and knew I'd rather have Draymond Green on my team than most of the bottom half. This quantifies that.
I know you'll want to find out about Michigan's guys, so here you go. Only players included are those with over 30% of minutes played, so guys like Horford and Christian don't make the cut.
|Fr.||Tim Hardaway, Jr.||UM||1.93||0.7||2.1||1.93|
That's actually kind of worse than a lot of the Big Ten, but UM tends to roll flatter but deeper. Novak is better than at least half of other teams' 4th-best guys. I would put up the rest of the league, but this is getting long. Enough people take interest, I will. There you have the data; enjoy.
Edit: One point that needs clarifying - I was challenged on this by an FOV reader. The average team offensive rating is about 101 - therefore the average possession is one point. So if a steal takes away a possession, shouldn't steals take away one point, not two? No, because for the average possession to be worth a point, the successful possession must be worth two. A steal denies a successful possession, not an average possession. It's only appropriate to speak of taking one point off the board by denying a possession if that possession never begins in the first place. Once it's begun, the outcome can be assumed to be binary - either zero or two points. (One or three is possible, but they average each other out to two.) Therefore a steal prevents two points. And a block is half a steal because the offense is assumed to recover the ball half the time.