Tonight is the MLB All-Star Game and we’re smack in the middle of baseball season (with no football news to boot!). I’m a huge baseball fan and a huge stats fan so, naturally, I spend a ton of time reading FanGraphs and other statistically minded baseball blogs. WAR is one of my the most definite stats and one that I absolutely love. While batting average, OBP, OPS and all that are nice, the only real success metric that matters in baseball or any other sport is the number of team wins. WAR (Wins Above Replacement) actually computes how many wins a player may be worth.
I’ve long sought after such a stat for football, a sport that is years behind baseball when it comes to advanced statistics but it is getting better. Thankfully, when our stats guru George came on board last season, he opened my eyes to a bunch of different advanced statistical sites, one of which provides stats called EPA (Expected Points Added) and WPA (Win Probability Added). For my money, these are two of the best NFL stats around. I charted out the Steelers positional leaders in WPA and how they fair when measured against the best in the league after the jump.
Here’s an excellent explanation of WPA, which I’ll be using in detail below:
WPA starts with a Win Probability (WP) model of the game of football. Every situation in a game gives each opponent a particular chance of winning, and a WP model estimates those chances. The model created here at Advanced NFL Stats uses score, time, down, distance, and field position to estimate how likely each team will go on to win the game. For example, at the start of the 2nd quarter, a team down by 7 points with a 2nd down and 5 from their own 25 will win about 36% of the time–in other words a 0.36 WP.
On that 2nd down and 5, let’s say there is a 30-yard pass, setting up a 1st down and 10 on the opponent’s 45. Now that team has gone from a 0.36 to a 0.39 WP. The WPA for that play would be +0.03.
If instead the quarterback throws an interception returned back to the line of scrimmage, the opponent now has the ball at the 25, giving the trailing team a 0.28 WP. The WPA for the interception would be -0.08.
So we can use WPA to measure which Steelers added the most to the team’s chance of winning. It would be easy to take the top five highest Steelers in WPA and call them the most valuable, but that wouldn’t be accurate. Inherently, some positions are more important to WPA than others (quarterbacks vs tight ends, for example). Instead, I took at look at how the Steelers ranked when compared to their peers. A wide receiver who had the highest overall WPA out of any receiver at 2.7 i is more ‘valuable’ than a quarterback who had a WPA of 2.8 but was in the middle of the pack of all the signal callers.
Here are how the highest rated Steelers compare at each position to the best in the league:
| Player | WPA | Rank | League Leader | WPA |
| Roethlisberger | 2.14 | 10 | Brees | 4.88 |
| Mendenhall | 0.06 | 24 | McCoy | 1.22 |
| Ward | 1.36 | 14 | White | 2.54 |
| Miller | 0.09 | 23 | Heap | 1.73 |
| Keisel | 0.88 | 32 | Allen | 2.01 |
| Timmons | 2.74 | 1 | Timmons | 2.74 |
| Polamalu | 2.43 | 1 | Polamalu | 2.43 |
| Gay | 1.69 | 4 | T. Williams | 2.55 |
Looking at the chart, a few things stand out:
– WPA does not like the Steelers offense much, especially Rashard Mendenhall.
– WPA places a lot of value on critical, late game plays. So while Willie Gay dropped a handful of interceptions and generally looked lost in coverage for much of the year, he had 2 sacks, scored a special teams touchdown and blocked a crucial punt so he rates as the 4th highest cornerback in the league. WPA heavily factors in what Mike Tomlin would call “splash plays.”
– Timmons and Polamalu represent the highest WPA added in the league for linebacker and safety.
– It isn’t shown in the chart, but the Steelers linebackers finished 1-2-3 in WPA added for 2010 (Timmons, Harrison, Woodley). James Farrior wasn’t far behind, finishing in 7th. The Steelers had four linebackers listed before any other team had two. That is remarkable.
In sum, the two most valuable players for the Steelers according to WPA were Lawrence Timmons and Troy Polamalu. Rounding out the top five would be James Harrison, LaMarr Woodley and William Gay.
Obviously this isn’t a perfect stat, but there is definitely some merit to these numbers. Gay aside, I feel WPA represented the Steelers pretty accurately in 2010.
