Running the Numbers: Three Hurdles Zac Stacy Has to Overcome to Be a Fantasy Stud
At the risk of being ostracized by the RotoViz community, I’m here to pump the breaks a little on Zac Stacy. First, let me say there are probably great reasons why Stacy is a RotoViz favorite. Shawn Siegele compares his agility to that of Ray Rice, Matthew Freedman lays out why he’s likely to produce at top 30 season, and Jon Moore shows you how he just might be the SEC’s best workhorse. When a player is the subject of no less three articles by three different RotoViz writers, it probably doesn’t pay to bet against him. But I couldn’t let my voice go unheard.
My new RB model uses three different factors to score college prospects entering the NFL: Draft Slot, Rushing Dominator Rating (DR), and Speed Score (a metric that measures how fast you are for your weight). Without getting too deep into it, let me say this about Agility Scores: I don’t doubt that Shawn’s work on Agility Scores is worthwhile. I just have a hard time knowing how much Agility should count for when it’s not available for a large number of players because they don’t participate in the 3 cone drill, the short shuttle, or both. I have a hunch adding Agility Scores to my model would make it even better, and I’ll be working on a way to factor that in. But for now, it’s not a part of my model.
Now, decomposing why my model doesn’t like Stacy:
Draft Slot – I’ve found that generally guys who are drafted in the 3rd round or higher tend to do better in the NFL because a high draft pick implies 1) the team thinks highly of his skill set (and they probably bet other teams do too), and 2) the team intends to use that running back in their offense. Stacy going in the 5th round doesn’t inspire me. If someone thought he were talented enough he would have gone before guys like Knile Davis, Stepfan Taylor, Joseph Randle, and Chris Thompson. BUT…NFL scouts and their GMs can can certainly be wrong about a player. And as we know, running backs are being devalued in the NFL. So, set draft slot aside for a second.
Speed Score – Stacy’s Speed Score of 100.8 is basically dead-on average. I won’t ding him, but it doesn’t make me like him any better either.
Rushing DR – Stacy’s most damning attribute for me is his his lack of domination of Vandy’s running attack in 2012. In developing my model it became clear that the most successful NFL running backs tended to account for 65% or more of their teams’ rushing yards and touchdowns. To further illustrate, the average Rushing DR of all backs in my sample who posted a top 30 is .56, and the average for all backs to post a top 20 season is .60. If you want to look at multiple top 20 or 30 seasons, those numbers go higher. At .46 Stacy didn’t even account for half of Vanderbilt’s rushing production. He shared yards and TDs with teammates Wesley Tate and Brian Kimbrow, a Junior and Freshman respectively. Tate is similar in size to Stacy and Kimbrow seems to be the smaller speed type. Sound familiar to any players on the Rams roster? If Stacy can’t claim a majority of rushing yards and TDs from the guys on his college team, who’s to say he can beat out Pead and Richardson (let alone just hold them off). Don’t sleep on Ganaway either (who, by the way, still managed a .51 Rushing DR with RG3 taking a .22 share!).
Let’s look at a table of other players with similar weights and low Rushing DRs. I didn’t control for 40 time because I wanted to show the effect that variable has. I’m using the minimum productivity threshold here: all of these guys had at least one top 30 RB season. (DA Score stands for Draft-Agnostic Score. I remove the draft slot factor from my model and re-normalize the Rushing DR and Speed Score factors so I can look at what my model thinks of a prospect pre-draft).
|Player||Model Score||DA Score||College Year||School||Draft Slot||Height||Weight||Forty||Speed Score||Rush DR||Vert||Broad||Shuttle||3 Cone||Agility|
|Vick Ballard||-0.4||0.17||2011||Mississippi State||170||70||219||4.59||98.7||0.51||33.0||115||4.19||7.03||11.22|
|Tatum Bell||0.74||0.38||2003||Oklahoma State||41||71||212||4.37||116.3||0.46||38.5||117|
|Joseph Addai||0.79||0.27||2005||Louisiana State||30||71||214||4.40||114.2||0.45||38.5||125||4.48||7.10||11.58|
|Domanick Davis||-0.11||-0.53||2002||Louisiana State||101||69||213||4.58||96.8||0.36||32.5||112||4.47||7.32||11.79|
|Doug Martin||0.94||0.66||2011||Boise State||31||69||223||4.46||112.7||0.55||36.0||120||4.16||6.79||10.95|
Does anyone on that list excite you? If they do, it’s probably because they had an elite Speed Score (and therefore do better on the Draft-Agnostic Score). Portis might be the most optimistic projection for who Stacy could be. On the less favorable side, he’s a shorter version of Ladell Betts.
At the bottom you’ll see I threw in the two guys Stacy most often gets compared to – Rice and Martin – because of their similarly elite Agility Scores. It turns out, apart from their height and Agility metrics, they’re not really all that similar. Rice and Martin both have better Speed Scores (much better in Martin’s case) and when it comes to Rushing DRs it’s not even close. Rice was an absolute stud and Martin is at least solid. Throw in their draft slot and it’s game over. The Agility similarity probably counts for something, but I’m not sure it’s enough to make up for Stacy’s other deficiencies.
For what it’s worth Adrian Peterson only had a .44 Rushing DR, but that’s only because he didn’t appear in 7 of Oklahoma’s 14 games that season (including the Fiesta Bowl). Pretty impressive he still managed that .44, when you think about it. Of course he also has an elite Speed Score of 115 and was drafted 7th overall – not really a comparable. Unfortunately for Stacy, he did play in all 13 Vanderbilt games in 2012.
So, is Zac Stacy the next Ray Rice, Doug Martin, or even Clinton Portis? You be the judge…all I know is I won’t be taking Stacy unless he somehow falls into the late second round of rookie drafts. Thanks to the other writers on this site, you can bet that won’t happen.