Raw numbers can tell you a lot about the games that are played on Sunday – occasionally Thursday, Monday, or Saturday – but they can also lead a person down the wrong path. Anyone who has ever set foot down the path of discussing sports on the internet has seen someone making an argument that seems insane, with strings of data to back up their seemingly insane claims. Statistics are not about raw data, and you can usually tell a flawed argument by how many statistics back it up, vs. how many statistics are required to refute it. Each week I will be going over one or two interesting statistics for the Lions, and going over what they do and more importantly, do not mean.
On 14 carries this preseason Theo Riddick has gained 67 yards for an average of 4.8 yards per carry. Many Lions fans were hoping to see Riddick take a major step this year, as Riddick’s mere presence on the field last season tipped the defense off as to whether the Lions were going to run the ball or pass. Riddick carried the ball 43 times, and personally caught it 80 times. Without even getting into details about snap counts it is pretty clear that the Lions were going to throw the ball far more often than not, as we are not even looking at the pass plays where Riddick was not Matthew Stafford‘s target. Compounding this problem was the fact that even though defenses had little reason to expect a running play – making any time there was a hand-off a bit of a surprise – Riddick averaged only 3.1 yards per carry last season. The generally accepted line of competence in the NFL is four yards per carry. Theo Riddick was under it last season, but has been over it this season, clearly he has made the jump that we were all hoping for…right?
Not So Fast Chief
The first flaw in this argument is immediately obvious: 14 carries is way too small a sample size to draw any sort of conclusion. Even if we were to ignore that, a common technique when examining data is to remove the outliers, results that are rare, and significantly outside the norm. In this case an outlier would be Riddick’s single run which accounts for more than half his rushing yardage in the preseason. Removing this best result and the corresponding worst result, because in analyzing statistics the key to an accurate picture is to look for what the numbers tell you, not to seek numbers that back up your theory, a more accurate statistical picture is drawn. In the 12 carries between the best and worst result Theo Riddick managed this preseason he gained 36 yards for three yards per carry.
So What Have We Learned?
Nothing. The sample size of 12 can’t be used to prove anything unless it is overwhelmingly constant; a punter shanking 8 of 12 punts for example would be more than enough proof that he was a bad punter. Even if it does point to Theo Riddick being exactly who we thought he was, making that argument is not based on statistics. That argument can be based on the eyeball test telling you that the 34-yard run was a result of an entire defensive unit deciding that tackling wasn’t part of their job description and Riddick not just going down from an impact. Riddick’s yards per carry without that significant aberration fits within the parameters that the rest of the team’s running backs have produced. All running backs with 10 or more carries fit within the range of 2.9 to 3.3 yards per carry, with only Riddick’s single run putting him outside the expected range. Statistically speaking Theo Riddick has not really improved.
Kick Return Battle Royale
Dwayne Washington has put up some gaudy return numbers. The problem with using game data to look at kick returners is that there are just not that many kick returns. A running back can receive as many carries in a game as a returner will get opportunities to bring back kicks in an entire season. But let’s look at Dwayne Washington’s kick return numbers despite the admittedly small sample size of four. 159 return yards on four returns gives Washington an average of 39.8 yards per return. Washington, much like Riddick gained more than half of those yards in a single event, his electrifying 96-yard touchdown return that reminded people that a 4.4X 40 yard dash time is still really, really fast.
Removing this outlier leaves Washington with three returns for 63 yards, an average return of 21 yards per return. The other two top candidates for the job are Andre Roberts, and TJ Jones (21, and 21.3 yards per return respectively) who have had roughly equal opportunities. So what arguments could be made based on these numbers? Again, the sample size makes “proving” anything impossible, but would it be a stretch to say that Washington brings the same level of production in the return game as the other two candidates, but has the potential to create more big plays than his competition?
What About the Other Guys?
We may not have much data on Washington, but what about Roberts and Jones? According to pro-football-reference.com Roberts has 53 career returns for an average of 24.5 yards per return with one touchdown to his credit, recorded last season – making it unlikely that he has lost a step since performing the feat. Jones has five career returns for an average of 21.2 with a long return of 34 yards prior to this preseason. The sample size for Jones makes conclusions premature, but the stats that are there are not impressive and say little to the potential for better results. Again, Jones has proven nothing and may yet explode in to a career as a great return man. He has not done so yet, or even flashed the ability to do so in his numbers. Roberts has offered the uninspiring 1/53 touchdown ratio, but has put up a career return average for multiple teams that says he is better than his preseason average of 21 yards per return might indicate, likely a product of limited sample size.
So what conclusion can we draw?
Taking the sample sizes and associated constraints into consideration, Jones and Washington are unknowns, while Roberts is a known quantity. Roberts has shown a career of being a decent if not spectacular return man, who will consistently produce an above average return. Jones has put nothing on a football field that would lead to a conclusion that he is capable of more than he has produced, and Washington has shown that if the crease for a TD is there, he can exploit it, and when it is not, he is likely to get as many yards as Jones. Statistically speaking, this makes the kick return competition a two man race between Roberts’ consistency, and Washington’s big play potential. Jim Caldwell being an extremely risk averse coach, I am betting Roberts gets the nod.