Yesterday, I decided to put the numbers against the narrative in regards to the argument that Notre Dame Stadium’s grass field hinders the defense. I found that there really wasn’t much of a difference at all, despite the fact that the grass field quite visibly disintegrates by November.
So today, we will look at the defensive side of the ball and see if there is any noticeable differences there. After all, perhaps Notre Dame may want to tilt their home field advantage towards their defense, especially since it propelled them to a title chance in 2012.
We will do the exact same splits and comparisons that we did yesterday (Edit: For clarification, like yesterday these stats are from all four years of the BK era). Let’s start with the general turf/grass split.
The first thing that immediately pops out is that Notre Dame struggled against the past more on field turf than on natural grass (just over a 40 yard difference). Even more interesting is the fact that opponents attacked Notre Dame through the air just slightly more often on grass surfaces. Perhaps there may just be something to the turf…err…grass monster being a 12th defender for Notre Dame on the pass.
Also, it’s impossible not to notice that Notre Dame grabs more turnovers per game on field turf than on grass. The differences appear to be quite negligible; however, it is a little interesting to see that pattern in juxtaposed to the apparent weakness the ND defense has against the pass on turf.
Like I pointed out yesterday though, the focus should really be on Notre Dame’s grass it self, so below are the splits that further define away/neutral site games on grass in comparison to home games.
The gap in the passing difference widens even further when comparing field turf games to games at ND Stadium (nearly 50 yards difference). However, Notre Dame gives up around 30 more yards on the ground at home than they do any other playing surface.
When looking at it this way, it almost appears as if ND has to pick their poison. Do you prefer to potentially expose yourself to a passing game or potentially run the risk of losing the battle in the trenches?
As with the offensive comparisons, play calling and turnover differences remain negligible.
Now of course comes the big question: what happens when the the grass at ND Stadium turns into mush?
As time goes on, the Irish secondary continues to improve with a 20 yard drop in Aug-Sept to October followed by an additional 30 yard drop when the field is at its worse in November. This seems to make sense as opposing players would have more and more issues as time goes on.
Interestingly enough, the rushing defense stays within 10 yards difference in each time period. This particularly interests me as it completely conflicts with what we saw in the offensive comparisons where performances were both all over the map and easily explained away by the level of competition faced. Here, the performances are incredibly consistent, especially at home, meaning that we can feel fairly comfortable in what the pattern in the passing defense shows us.
These splits also seem to confirm the pattern of the passing defense struggling far more on field turf. Save for October, all other months saw the Irish struggle with the pass in comparison to their performance on other surfaces. This again seems to continue to point us in the direction of ND’s grass actually being an advantage.
For our last comparison, we head back to our head-to-head comparison with Michigan:
The pattern once again holds: passing defense destroyed on field turf, but the rushing defense struggles on ND’s grass surface. In this case though, the differences are even more pronounced with a passing yards allowed difference of over 120 yards and a rushing yards allowed difference of over 80.
The conclusion? It appears we had the right idea for the narrative of ND’s grass causing certain offensive struggles; however, it is not ND’s offense, but those of their opponents.
It does appear that there is some level of home field advantage to be had with the grass playing surface. Opposing passing offenses struggle; however, this does seem to come at the cost of the Irish’s rushing defense. If the decision were to be made purely on this coin flip, I’m not sure which direction you would go.
While limiting passing offenses seems to be the obvious answer, especially in terms of limiting explosive plays, I’m not sure that potentially opening ND up to the run would be a wise trade off. After all, getting throttled on the ground could easily lead to a gigantic time of possession swing that would lead to ND’s defense struggling to get off the field and thus still exposing them to the threat of an explosive play due to fatigue alone.
Or perhaps Notre Dame would like to remove the inconsistency of a poor field completely and take the risk of struggling against the pass. As we have seen, the true home field advantage gain really doesn’t show itself until the field starts to wear down later in the season. It could definitely be argued that the wait isn’t worth it, especially since Notre Dame typically fields it’s strongest opponents in the first half of the season.
In the end, while there are definitely more visible difference on the defensive side of the ball, I believe we are still left in a coin-flip situation. I do not believe that I have shown enough clear evidence that grass would be a clear statistical advantage for Notre Dame despite some advantages appearing in this exercise. It will be just another part in the pro/con discussion of which direction to go in.
The real “trick”, in my opinion, would be how Notre Dame decides to “own” there field. That is, would they prefer to remove as many random, uncertain variables in a game as possible, tilting the scales more towards pure talent and speed? Or would they prefer to be a team that’ll just, for a lack of a better term, “play ugly” as the season wears on?
Or will Notre Dame manage to find a way to turn the harsh climate and soil of Notre Dame Stadium into a happy middle-ground of natural grass?
I’m sure that these, as well as many other questions, are exactly what Jack Swarbrick is weighing right now. I’m not sure there is a clear “right” answer to this one.