Kain Colter and Trevor Siemian: A Metrics Breakdown


(Promoted from the fanposts, a nice look at what Kain Colter and Trevor Siemian do.)

This is a piece I’ve wanted to put together for a while. As a primer, in the past I’ve analyzed the college statistics of NFL draft prospects (you can find that work at and One of the perks of that is I’ve gotten some interesting data on Northwestern players that I’d like to share. As a note, the data is charted from every game and is accurate. When I write about draft prospects I look to project certain stats to the NFL, I’ll leave out some of those analytics in favor of comparing the play of both Colter and Siemian. Let’s get to it.

Where Did They Throw the Ball?

The following chart reflects the percentage of total attempts thrown to different depths on the field.This is an interesting comparison because it really shows you how Mick McCall designs the offense around each individual player. The "zones" as I’ll refer to them account for where the receiver caught the ball so as to not be influenced by yards after the catch and receiver ability.


  • Notable of course is the fact that Kain threw 20+ % more screens than Trevor did. This is to be expected given their relative styles of play, but 34.6% screens is a good chunk of his passes. If you’re an opposing defense you have a roughly 1/3 chance that the next play will be a screen pass against Colter. I’d imagine you’d want to alert your players to take more risks given that info.
  • Siemian on the other hand makes up for a distinct lack of screens with shorter and intermediate throws. Approximately 68% of Trevor’s passes are in the 0-15 yard range which is distinctly higher than the BCS average of 58%.
  • The two don’t throw a notable amount of passes in the 16+ deep range. Siemian’s 20% of attempts is around the BCS average while Kain goes deep slightly less.

How Well Did They Throw It There?

This chart represents their accuracy at each depth. Like the attempts, it only takes into account where the receiver caught the ball or was targeted rather than accounting for YAC. The color coding is in reference to the BCS average completion percentage. Green being better, yellow being a push, etc.


  • Wow is Siemian just not good at throwing screens. I’m not sure if there’s some other factor in play, but the fact that his screens are only being completed at a 45.5% clip is bad. He threw 24 screens last year and only completed 11. You need that to be a higher percentage play when it counts.
  • It’s clear that Trevor has the short passes down. A staple of NU’s offense, the 83% completion percentage in that zone is similar to past draft picks Andrew Luck and Russell Wilson.
  • I’m very impressed by both Siemian and Colter’s accuracy in the intermediate range. When I’m looking at draftable prospects, I like to look at the intermediate throws as they are typically your ‘NFL’ throws. I’m particularly impressed by Kain’s 65% accuracy. He threw in this zone a non-insignificant 28%, which makes it something the defenses have to respect. That type of accuracy can keep a defense from edging their coverage up.
  • Let’s just be brutally honest here, they were both really bad at throwing deep balls. I’m not sure if this is on the wide receivers for a lack of separation, poorly timed attempts or just bad accuracy. The thing that makes this worse is that Siemian threw these passes 20% of the time, at the BCS average and his completion percentage was 4th worst in the BCS last year. It seems unwise to be taking that many shots if you can’t hit them consistently.

How Were They In the Clutch?

We’ll pick out a few key stats to look at in this section. When I look at draftable QBs I emphasize these stats as indicators, but we’ll keep it light.

3rd and 8+ Completion %:

Colter: 52.6%

Siemian: 34.6%

  • I don’t have the stat on how often they were in these situations, but the difference is striking. We do have to worry about factors confounding this stat. As noted above, Colter was much more likely to throw short, easy to complete passes. His comp % could be inflated by short passes in front of the sticks.

Comp % Against the Blitz:

Colter: 70.3%

Siemian: 50.8%

  • Again we do have to consider shorter passes, but a 20% completion percentage difference is quite large. Against the blitz it’s a 50/50 shot with Trevor, but Colter completed 70% of his passes which is higher than his actual overall completion percentage. The 3rd and 8+ completion percentage, throws against the blitz and ability to run leads you to wonder if he should be the QB on more 3rd and long situations.


The nice thing about comparing these numbers is that they both play with the same wide receivers. We’re not comparing a QB that has Sammy Watkins and another that had no weapons. It is of course impossible to project how the QBs will grow, but Colter’s stats have to be encouraging for him as a passer. Sometimes he gets dinged for a tendency to pull the ball down and run, but at a minimum his stats keep up with Trevor’s. I’ll let you make a judgment on how they compare.

"Now Greg", you’ll say, "Siemian was put in more difficult situations. He had to come in during the 4th quarter and to convert more 3rd and longs. That will definitely pull down his stats!" Yes it’s true. There are many confounding variables in football stats, they’re unlike baseball or even basketball analytics and they’re difficult. However if you take them for what they are they can be helpful. Understand that these stats aren’t the end all, be all – use them as a tool in forming a better opinion. Thanks for reading, hope you enjoyed.