Big Ten Geeks Glossary

As Big Ten Geeks we use plenty of stats that you don’t see on your ordinary hoops blog. Why? Because we’re basketball geeks. So use the handy glossary below and let us know if you have any other questions. And be sure to check out Dean Oliver’s book Basketball on Paper since we draw plenty of inspiration from his work.

Offensive Rating: This number is supposed to be the one number that captures a player’s “points produced” per 100 possessions (so above 100 is good, below 100 is not so good). The formula, which you can read about in Oliver’s book, is very complicated (because Oliver is very thoughtful about his variables). The inputs are, generally speaking, field goals (and misses!), free throws (and misses!), assists, and offensive rebounds. This stat, however, does not change with playing time. In other words, you can play one minute and have a great “ORtg,” but it doesn’t make you the best player in the country (far from it). In that respect, it’s like batting average for baseball (or for SABRs, like OPS or EqA).

I think ORtg checks out as a good stat, but in doing so much simplifying, the stat obscures. There are many ways to get to an ORtg of 100, and I like knowing which way a player takes. Moreover, I worry that by throwing one number out there, it comes off like some made-up number that lacks credibility. Nobody is reaching into a hat and pulling out “107.3″ for Goran Suton – that number comes from real performance – but I understand the frustration. Therefore, I tend to use ORtg for brevity’s sake, but I prefer to give more information where I can.

Shot Percentage: This stat is simply the percentage of team shots a player attempts while he is on the floor. Intuitively, 20% is the average (5 guys on the floor, and it has to add up to 100%). A percentage of 15% or lower is strictly a role player who does not look to score often. A player at 25% or above is a go-to player for his team. This stat is tremendously important because good shots are limited. What I mean is that, over a course of a season, there are only so many “good shots” for any given player. Nobody out there is getting 300 wide open 3 pointers over 30 games. So that means players who are taking a lot of shots are often taking a lot of difficult shots as well. That’s not a bad thing because somebody has to take them. Taking a high percentage of shots, while maintaining a high conversion rate, is what we look for in First Teamers. It’s only a bad thing where these same guys are throwing up bricks, with an eFG hovering around 40%. Speaking of which…

Effective Field Goal Percentage (eFG): This stat is exactly like field goal percentage, except it counts a made three pointer 50% more (to reflect the 50% higher point value). If two guys have an identical FG% of 50%, and one shoots only 2s, while the other shoots only 3s, which do you want? Effective Field Goal Percentage captures that.

Offensive Rebounding Percentage (OReb%): This number is the percentage of rebounds off missed shots captured by a player. It’s much better than offensive rebounds per game, because it recognizes opportunity. If the team doesn’t miss, there are no offensive rebounds to grab. Conversely, if the team can’t buy a bucket, then this stat will go through the roof. I think Gasaway said it best — “missed shots” are the “at bats” of rebounds. Defining a “good” OReb% is different by position. For post players, above 10% is good, and anyone hitting 15% is among the very best in the country.

Defensive Rebounding Percentage (DReb%): Same thing, but now with opponents’ missed shots as the denominator. Defenses get more rebounds than offenses (by about 2:1), so the scales shift. For post players, above 15 is decent, 20 is very good, and only a handful of players in the country will hit 30.

Assist Rate (ARate): Simply the number of player assists divided by field goals while he is on the court. Just measures how often a made field goal comes from a player’s pass. Again, this takes opportunity out of the equation…somewhat. If the team is a bad shooting team, the assists per game would be lower than they would if the team could shoot better. By putting team FGs into the denominator, we fix that. Of course, a player can still have an unlucky night, where the team seems to prefer missing mostly when he passes them the ball. Of course, we expect these things to even out over the season. I generally define a PG (or someone with PG skills) if the ARate is above 20. Above 30 is very good. Some guys can even push this number to 40.

Turnover Rate (TORate): The percentage of “personal possessions” that end in a turnover. This one is tricky, and very dependent on position. PGs have more TOs, because they do so much dribbling and creating. On the other end of the spectrum are the “catch and shoot” players, or “catch and do nothing” players (like Lance Stemler). You can live with a PG with a TO Rate above 20, but above 25 isn’t very good. Post players are ideally below 15.

Block Percentage: Simply the percentage of opponents’ 2 point FGAs that are blocked by a player while on the court. It’s two pointers because, well, three point blocks are rare and including them would only dilute the pool so that everyone looks more similar. Anything over 7 or 8 is great. The best shotblockers are the ones who don’t sacrifice rebounding.

Steal Percentage: The percentage of possessions on which the player records a steal. Small numbers here, and I tend to think that players above 3% have a real skill with it. A very small handful in the country get above 5%.