What separates successful WNBA Draft prospects from unsuccessful prospects?

Not everything that can be counted counts, and not everything that counts can be counted. -Albert Einstein

— Vince Minjares (@PlayerLearning) November 1, 2012

Perhaps the easiest way to demonstrate the value of statistics and more specifically the value of looking at the right statistics is to look back at the track record of success of volume shooters in both the NBA and WNBA draft.

And really we're not talking about the mysterious advanced statistical sorcery of magic wizards, but simple things like the percentage of attempted shots a player makes.

Every year in both the NBA and WNBA draft, at least an exciting player at a major program fools a general manager into selecting them in the first round with a high scoring average that obscures a low shooting percentage. If they make the team/rotation, they get their chances to make an impression in their rookie year, eventually fall out of favor with the team that drafted them when they realize they were looking for actual points instead of attempted points, and then float around the pro basketball world as teams try to find a role for the player who was once such a promising scorer.

Every now and then, you'll get an Allen Iverson, a player who seemingly shoots indiscriminately but is so dominant that he actually makes quite a few of the shots he takes. Similarly, sometimes you'll find a Riquna Williams whose inefficient volume shooting in college might also reflect a transferrable ability to create shot attempts, which can certainly be valuable in certain situations. Along those lines, sometimes a point guard will be look like a poor shooter simply because their college team demanded that they do it all: pass, score, and figure out when to alternate between the two during matchups, which is a valuable skill even if the statistics aren't perfect.

But caveats aside, looking at scoring efficiency rather than scoring average tends to be the best way to separate WNBA prospects from non-prospects and the fact is that after you sort all of that out you're left with a very small pool of strong prospects.

Statistics will never capture everything that counts: intelligence, leadership, maturity, and work ethic among other things can go a long way to overcome or undermine statistical indicators. But a large part of drafting well comes down to managing risk; nothing, even the exact quality of production of a consensus top pick, is certain in a draft context. Ultimately, the best general managers are able to look at a player's entire portfolio - film, statistics, and "intangibles" - and discriminate between the information that matters and that which is either irrelevant or less significant.

The 2013 WNBA Draft is deep in the sense that there are a number of athletes who have been very productive and even elevated the profile of their college programs. But upon further scrutiny, one thing that really stands out is that a number of highly touted prospects entering this college season are productive in terms of averages yet not particularly efficient in terms of rates of production. And although every player and her fans wants to believe that she can create her own legacy, there is a historical record that of successful and unsuccessful profiles that is extremely useful in projecting the future success of a given prospect. Furthermore, as it turns out it's much easier to look back at the past and figure risk factors for an unsuccessful transition from college to the pros than vice versa - in other words, figuring out who probably shouldn't be among the 36 players drafted is often much easier than figuring out exactly how much they will contribute to a WNBA team. Nevertheless, even in a draft that everyone considers deep, there are a number of statistical indicators that might help us separate great college players from great WNBA prospects and put prospects in tiers for a draft board rather than a strict rank-order hierarchy.

The following are a few major statistical "red flags" that have limited NCAA Division I players' chances at a successful transition to the WNBA in recent years.

Red flags for WNBA draft prospects

Perimeter scorers with low shooting efficiency

Some people like to harp on guards who can't shoot, but some of them are occasionally successful as described above. A harbinger for struggling to make the league is being a volume shooting non-point guard 5'7” or under who doesn't score efficiently. There is currently one notable exception in the league right now: Riquna Williams and a major reason for that is that she is just so athletic that she can continue getting her shots in the pros.

As an extension of that, wings with 2-point percentages under 46% tend not to be very successful prospects, although there were two rookie exceptions just this past WNBA season: Williams and Natalie Novosel. Another exception coming out of college was Karima Christmas, who now has a championship ring. There's potentially an adjustment that helps to explain that, but we're not going to disprove a rule with exceptions for now - Christmas and Williams had physical attributes that helped them overcome the poor shooting and Novosel played limited minutes on the worst team in the league. It's not common for a wing to enter the league with a low 2-point percentage and succeed.

Examples from the 2012-13 senior class: Sugar Rodgers, Georgetown; Nicole Dickson, Memphis; Whitney Hand, Oklahoma

Poor rebounding guards

A large part of the reason why inefficient scoring tends to hurt perimeter scorers differently from other positions is that they tend not to contribute in other ways if they can't score: point guards can run an offense and pick up assists, post players can get rebounds.

Nevertheless, although we typically don't expect guards to come into the league and contribute much on the boards, really poor rebounding wings (under 3% offensive rebounding percentage) tend not to do all that well. Again, point guards are a major exception to that although rebounding helps those that meet the other criteria.

What poor offensive rebounding - especially in conjunction with a low free throw rate and sub-point guard assist ratio - tends to say about a guard is that they're limited athletically in terms of their ability to impact a game.

Example from the 2012-13 senior class: Alex Bentley, Penn State; Lindsey Moore, Nebraska

Low usage rates

For all we want to talk about how the WNBA is about fundamentals and teamwork, the draft record pretty clearly reflects that players with low usage rates in Division I basketball don't tend to be very "successful". Typically, falling under a usage rate of 18% at any position limits a players chances for WNBA success (with an exception for centers because their ability to score at a high rate typically depends on the efficiency with which their guards get them the ball).

The reason for this might seem obvious at first: if you can't easily create a shot for yourself and aren't a point guard (who can create shots for others), you become a liability to an offense at the next level. However, that doesn't quite explain why low usage players (guards especially) struggle to even get drafted: it might be equally plausible that players with low usage rates don't stand out to scouts because they don't score much or get knocked for being passive.

In any event, we can probably add some nuance to the shot maker vs. shot taker dichotomy: between inefficient shot-takers and efficient "limited shot takers" (players with low usage percentages), the former might have an advantage in terms achieving success. There are a number of potential explanations for that – that have little to do with how much a player contributes to her team, by the way – but non-shot takers outside the point guard position could almost be considered non-prospects.

Examples from the 2012-13 senior class: Jenny Ryan, Michigan; Kelly Faris, UConn; Taelor Karr, Gonzaga; Haley Steed, BYU; Adrian Ritchie, Wisconsin - Green Bay

Post players with low offensive rebounding numbers

It might be obvious why this one becomes a red flag: offensive rebounding is a skill distinct and more significant than defensive rebounding for draft prospects in the NBA and WNBA for what it represents as much as generating a second shot.

There are a lot of tall players who get defensive rebounds simply by being tall and typically positioned near the basket in an advantageous position to get to the ball. Offensive rebounding, in contrast, takes a combination of athleticism, basketball IQ, instinct, a whole bunch of neurological stuff, and most of all effort. So tall post players (even 6'3" and above) who don't get a high percentage of offensive rebounds sometimes struggle to meet expectations at the pro level because one of those things isn't present.

Examples from the 2012-13 senior class: Carolyn Davis, Kansas

Power forwards 6'1” and under

I know this one sounds arbitrary and with wingspan mattering more than "top of the head" height it sounds misguided.

Yet the fact remains that college power forwards 6'1” and under simply aren't very successful prospects and those that are were very efficient scorers in college (2-point percentages of 52% and above). Even then, the track record for success isn't all that strong: only five college power forwards under 6'1" lasted the season on WNBA rosters last season and one - Danielle Adams - is something of an anomaly because she was such a good passer and 3-point shooter in college.

This flag isn't so much about success vs non-successful as much as quality: Adams and Sophia Young are obviously prime examples of players who have overcome being undersized to carve out a niche for themselves, but players like Alysha Clark and Ashley Walker have struggled to even make teams. Where it really does become a matter of roster-worthiness is when undersized power forwards weren't very efficient scorers in college.

Examples from the 2012-13 senior class: Destiny Williams, Baylor; Morgan Stroman, Miami

Centers with true shooting percentages under 55%

Centers are an interesting bunch of prospects because a lot of what they do offensively depends on their guard play. So if they're not efficient scorers, a major question for them appears to be whether they can help the team in ways other than scoring. That's where their value added rating comes in, which is their Model Estimated Value minus their points scored.

Centers with a value added rating over 2.22 tend to do well even if they are inefficient scorers. Since 2005, there are three examples of value added being a “protective factor” for a player with a low true shooting percentage coming out of the NCAA: Nicky Anosike, Janel McCarville and Krystal Thomas.

In other words, inefficient scoring centers have a pretty tough time making the league.

Examples from the 2012-13 senior class: Kelsey Bone, Texas A&M

Inefficient ball handling

ESPN's John Hollinger has made the point in his NBA draft rater that low pure point ratings are actually a red flag at any position (adjusted by position) and that tends to be the case in the WNBA as well though looking at why a player has a low pure point rating tends to be important.

For point guards, not having a high pure point rating is a problem to begin with so dropping into negative numbers is obviously a bigger problem.

For wings, the problem with a low pure point rating should be obvious: for players who end up in position to dribble and pass the ball more often, a low pure point rating reflects some combination of poor ball handling, passing, or decision-making ability. A wing that can't dribble or pass efficiently is going to be a limited player at the next level. But sometimes a high turnover ratio isn't a bad thing for a wing prospect: for high usage players, high turnover ratios can simply be a function of the player's aggression attacking the basket. Similar to what has been mentioned previously, when they get to the pros and are asked to create less the turnovers become less of a problem.

Post players with low pure point ratings (less than -6.00) are a bit more complicated - sometimes got those numbers because they played big minutes and didn't get a lot of assists meaning they had considerably less weighted assists than turnovers. However, that's not quite as big a problem as a post player who has a low pure point rating because they do in fact turn the ball over a lot (a turnover ratio of 15% and above). In addition, high usage post players sometimes turn the ball over simply as a function of getting more opportunities than they really should - with less touches in the pros, suddenly turnovers are less of a problem.

Still, a low pure point rating is a red flag that can limit a player's success even if they do end up making a roster and tends to be hard to ignore.

Examples from the 2012-13 senior class: Chelsea Poppens, Iowa State; Morgan Stroman, Miami; Markel Walker, UCLA; Kevi Luper, Oral Roberts; Jasmine Dixon, UCLA (2011); Chucky Jeffery, Colorado; Davellyn Whyte, Arizona

Mid-major players

People are obviously skeptical of mid-major players for good reason, but since 2005 about 50% of Division I mid-major players drafted have actually stuck on a roster for a season (25 of 48, which is a bit less than the rate of major conference players albeit there have been 250+ of those). Yet over the last five seasons, only six mid-major players have lasted on a roster for two seasons and only two (Amber Holt and Leilani Mitchell) have been a full-time starter at any point in that time.

So what should we make of mid-major statistics? If mid-major lottery picks like Amber Harris and Courtney Vandersloot have struggled and only one has made it as a full-time starter as a rookie (Holt), should we just ignore them?

The one thing that really stands out about mid-major players is that they have been hurt by the 11-player roster limit - in terms of making rosters - more than almost any other large category of player (another category would be 3-point specialists, who are essentially non-existent in the league after the roster limit was imposed). A lot of those 25 that made rosters in their draft year didn't last more than a season. Most have bounced around. The last mid-major All-Star drafted was Candice Dupree.

But there's another angle on the mid-major prospect that can't be ignored: the last two seasons have been a testament to the value of patience with players coming from less prominent programs. Jessica Adair, Alysha Clark, Natasha Lacy, and undrafted Avery Warley are all examples of mid-major players who weren't immediately successful prospects but worked on their games overseas and returned to be solid rotation players.

Ultimately, the discussion of mid-majors is simply worth a separate article, which we'll get to later. But it's safe to say that some adjustment should be made for mid-major statistics.

So are all these players just non-prospects?

Just as yesterday's statistics were presented with a caveat about those being junior year numbers, every single one of these should be taken the same way - although each of the players listed above has a weakness that would be a concern if they were being drafted today, the fact is that they have a full senior season to improve upon those weaknesses (and reinforce strengths).

But looking at the junior season numbers in depth like this is useful: in addition to providing some idea of what specifically to watch for throughout the season among those who might have their names called on draft day, it gives us a baseline from which to gauge improvement. Some of these statistical observations may indeed indicate low ceilings for some of these players, but the reason these players are listed above instead of the hundreds of others who have statistics that make them a non-prospect is that even marginal improvement upon their weaknesses is almost certain to improve their status on draft day.

On draft day, it will come down to general managers weighing a prospect's strengths and weaknesses and figuring out whether she can succeed in their system.