Here is how Trevor Siemian’s NFL career is trending

If you read much of what I write here, you know that I like numbers. I like to see if we can learn anything from deeper dives into them. I particularly like trying to determine if what my eyes see in the game is the same story that the numbers tell.

This is going to be a piece about Trevor Siemian’s passer rating and it’s trend. If you don’t want to face the reality of what the numbers say about Siemian’s 19 starts into his NFL career, then stop reading now.

There were some overarching questions for which I wanted to find answers:

1. What do the trends look like in general for NFL QBs of you plot passer rating by game started? I’ve been told and read that it takes ~30 starts before NFL QBs “get it” if they are going to “get it”
2. How does Trevor compare to other recent QBs? Are there other starting QBs who have struggled in a similar manner to him during their first 19 starts? What happened to them in their careers?
3. How often does Trevor have an above average game? How often does he have a below average game? How does this compare to his “peers”?

First let me define my time frame. I only looked at QBs who started their careers in the NFL in 2010 or later. The passing game in the NFL has changed so much in the past 15 years that comparing Trevor’s first 19 starts to PFM’s or T*m Br*dy’s is not a valid comparison. For those who really want to do this (and I am fairly certain that I can guess who you are) I will provide a link to the spreadsheet (in google sheets) so that you can run the numbers yourselves. Using 2010 as my starting year, I found 31 other QBs who have started 19 or more games in the NFL besides Trevor. Below is the plot of passer rating vs start # for Trevor. Using start # “normalizes” the X axis and accounts for players who didn’t immediately start as rookies as well as QBs who lost significant time to injury.

I’ve included Brock Osweiler and Mike Glennon. Glennon was included because his data was found to be the most comparable to Trevor Siemian’s. The straight gold line is the league average passer rating for the NFL last season. If you look closely you will see that in Trevor’s 19 starts he has 9 that are above average and 10 that are below. The plot nicely allows us to see how good he was when he was good (he has 4 starts with a passer rating over 100) and how bad was he when he was bad (he has 4 starts with a passer rating under 70). We also see in the chart above just how bad Brock was with Houston last season (his first 7 starts were in DEN).

Now let’s compare him - graphically - to some other QBs that are linked to him.

Dak Prescott has been very good so far in his career. Carson Wentz is better this year than he was last. Colin Kaepernick has been erratic with some very good and some very bad games. Case Keenum has generally been bad.

So now you’ll see chart that compares Trevor’s first 19 starts to the first 30 (or so) starts for guys who only lasted two or so seasons in the NFL as starting QBs. Most of these guys became backup QBs (which is what some claim Trevor is).

So the good news is that Trevor appears to spend about half his time above average while most of these guys spent the majority of their time below average (with the exception of Griffin). If you want a graphical comparison of TS with any of these 31 other QBs (besides Brock), let me know in the comments and I’ll drop it in the comments section). Ideally I would have liked to place an interactive chart in the piece so that you could highlight different QBs to focus on them, but that’s still not an option in the wordsmithing app that SBNation provides us all.

So let’s move on to the tabular comparison of how often these 32 QBs had below average games (passer rating of 88) and how often they have above average games.

So here we see that Trevor is not bad in terms of his frequency of above average games (47%). That’s 12 of 32 and better than some highly paid and highly drafted QBs. I also found it interesting that his 47% is the same as Matthew Stafford, Marcus Mariotta, Jameis Winston and Sam Bradford and Ryan Tannehill.

Now let’s look at this idea that it takes 32 starts for an NFL QB to “get it” if they are ever going to “get it”. Here’s a comparative look at those QBs from the 32 who have started significantly more than 32 NFL games. This shows their average passer rating in their first 32 starts and compares it to their average passer rating in their starts after.

This data would suggest that Blake Bortles, Josh Freeman, Colin Kaepernick and Robert Griffin never “got it”. Can we as a franchise afford to give Trevor another 11 starts to show whether or not he is ever going to “get it”?