Deep Routes: Model Movement & is PJ Walker Overrated?

by Anthony Reinhard

Model Refresh and Week Two Preview

I updated my XFL elo model following week one action and unsurprisingly there was quite a bit of movement! The rating difference of two teams below is equivalent to the point spread between those two teams. Home teams will get an additional 2.6 points for home field advantage. New York gained more than a point in my ratings with their 23-3 win over Tampa Bay, which vaulted them from fourth to the top spot. Dallas, the top team in my preseason rankings, fell from a 1.40 rating to 0.31 when they were upset by St. Louis in a close game.

It was big week for Houston as they were the only team in the Western Conference to win during the first weekend. Despite only checking in at fourth, they boast the best championship odds at 22.7%. This more than doubled the 10.2% that I started them at to begin the season. Aiding their one game lead in the west was the official word that Houston will be hosting the XFL Championship Game in April. When I applied this to my model, Houston’s chances of winning the title jumped by about 4%.

You can follow along with my model at statbutler.com/xfl.

In week two, I’m leaning towards the home team in each game, but it is important to be aware that my rankings do not take injuries into account. This is particularly notable when it comes to quarterbacks. Dallas played last week without their starting QB Landry Jones. Jones was the first XFL player to sign a contract and likely had a lot to do with Dallas entering the season as the top team according to oddsmakers. Perhaps Dallas would not have lost on Sunday and suffered a ratings drop if Landry had played, but we can’t be sure. I for one, would be more inclined to believe that Dallas is better than their mediocre rating indicates and will be a favorite over LA this weekend. Incidentally, LA also was missing their starting QB on Saturday, so who knows?


The PJ Walker Hype Train

The breakout star of the first week of XFL football was Houston quarterback PJ Walker, who was assigned as Houston’s QB before the XFL draft. Walker is two and half years removed from Temple where he became the all-time leader in passing yards. After that, he was an on-and-off member of the Indianapolis Colts practice squad. On Saturday, Walker threw for 272 yards and four touchdowns against LA en route to a 37-17 victory. On the surface, Walker appeared to have a solid day, but some advanced metrics have me a little skeptical.

During this past NFL season, I learned about Expected Points Added (EPA) as a way to evaluate the success of a team. Put simply, EPA is the difference between the number of points a typical team would expect to score before a play and the number a points a typical team would expect to score after a play. EPA is great at capturing context. To use an obvious example, it can tell you that a five yard gain on 3rd & 4 in the red zone is far more valuable than a nine yard gain on 4th & 10 from your own 40 yard line. You can read more about EPA and what goes into it here.

As soon as I found play-by-play data on XFL.com, I was anxious to see how each team would stack up through the lens of EPA. Using the nflscrapR package in R, I applied the EPA model used for NFL games to each of the four XFL games. To be fair, the XFL has some different rules that will be difficult to adjust for in the immediate term. In my opinion, EPA is best used in this setting as a relative value, rather than as a literal interpretation as the number of expected points added. With that in mind, I created the following graph that shows the EPA per play of each XFL QB on QB runs, passes, and sacks:

It is important to reiterate that this should not be interpreted as saying Phillip Walker hurt his team more than helped due to his negative EPA. I do think it would be fair to say that plays made by New York Guardians QB Matt McGloin (third from the left), were more valuable on average. I was surprised that Walker came out as the fourth best QB of week one, so I looked a little deeper into the data.

The biggest hit to Walker’s EPA was his performance on 3rd and 4th downs. On late downs, Walker was 2/8 for 47 yards with a sack and a red-zone interception. The interception came with under five minutes remaining in a three score game, but still came in a high-leverage situation where the Roughnecks were well on track to pad their lead. His EPA on these plays overall was -1.08 EPA per play. The best way to describe this might be to say that if an NFL QB had made the same plays as Walker at the same times and positions on the field, he would have cost his team about 10 points on late downs. His early down numbers were far more promising (21 of 31 for 225yds and 4TD with 3 rushes/18yds), but came at times where his team was already likely to score. We’ll have to wait to see how this shakes out as nine plays is a very small sample.

Another factor that cost Walker some EPA was his team’s field position. Houston’s average starting field position against the Wildcats was on their own 45 yard line, the best of any team this week. Houston also had seven drives that began in LA territory. This obviously isn’t Walker’s fault, but it would be a fair expectation for the Roughnecks to score a lot of points based on where their drives began.

EPA can tell us how much production a player or team has generated, but in small samples like this one, it can leave out important details about how much credit the player deserves for that production. Enter Pro Football Focus (PFF), a website that evaluates players and teams on a grading scale from 0 to 100 based on their performance on each play. XFL.com posted a breakdown of some week one PFF grades that seem to back up what I’m seeing with EPA. Walker was ranked 5th of the eight qualifying QBs in PFF’s passing grades from week one with a grade of 64.7.

A final non-quantitative point is that LA fired their defensive coordinator following Saturday’s game. I’m inclined to believe that if he had been coaching the defense well prior to their week one loss, he would not have been fired after a single poor performance.

I’ll close by saying that I don’t know if PJ Walker is overrated. We’ve seen him play only once in this league and, to be fair, he played as well as he needed to. I’m just not convinced that he has been better than Cardale Jones or Jordan Ta’amu, who are both deserving of more praise at this point. Houston will host the BattleHawks to close out week two on Sunday and we’ll see how Walker fares against PFF’s second ranked defense.

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