Zack Greinke is one of my favorite baseball players of all time. Not everyone shares that opinion, as Greinke has some social anxiety issues and he rubs a lot of people the wrong way; but he’s a fascinating quote-machine and almost certainly one of the most cerebral, and interesting people in baseball. Greinke has always had a deep interest in scouting and Sabermetrics, and in his brief stint with the Brewers he was a fixture in their draft war room.

Perhaps my favorite thing Greinke ever did, was to conduct an experiment with his pitching over the course of a few seasons. Greinke has been good for ages, but it was never enough for him to be good — he also wanted a deep understanding of why he was good and how he could get better.

For those of you who don’t follow baseball, we know that there are a few things that pitchers have control over and a few things they don’t. That’s a bit of an oversimplification, and modern research has revealed that it’s more like there are some things they control a great deal, and some things they control less — but the point stands, and at the time Greinke did his little experiment he relied on FIP (Fielding Independent Pitching):

”I try to get ahead of the count without leaving it run down the middle in a person’s power zone... That helps me not walk guys, and then, when I get two strikes, I try to strike guys out. And that’s how I try to pitch, to keep my FIP as low as possible.”

The FIP stats are strikeouts, walks, and home runs, and historically FIP is a better predictor of future ERA than ERA itself. Greinke’s theory was that by focusing on the elements of FIP, that he could make himself even more efficient than he already was. That’s not how it worked out.

Greinke’s FIP did decrease significantly but his ERA didn’t, due to an increased Batting Average on Balls in Play (BABIP). BABIP is usually a fairly random statistic, fluctuating with a few bloop singles or diving catches, but in this case it’s more likely that Greinke’s strategy was having some unforeseen consequences. When you focus on raising strikeouts and limiting walks above all else, hitters are going to know that you will be throwing strikes, and strikes are easier to hit and hit hard.

Greinke doesn’t suffer failure well, and he eventually abandoned the experiment, returning to his former approach and repertoire, with extremely great success. FIP is a good statistic for quantifying a pitcher’s production, and it’s not controversial that strikeouts are good for a pitcher, while walks and home runs are bad. So why didn’t Greinke’s strategy work, and what does any of this have to do with Aaron Rodgers?

FIP and Interceptions

The problem with pitching to FIP is that FIP isn’t a recipe on how to pitch. FIP measures the good and bad things that happen while you go about pitching as well as you can. Minimizing walks to an absurd extreme will get you hit hard, and trading a few walks to fool a few additional hitters is worth it.

In the NFL, throwing an interception is seen as just about the worst thing you can do, and no one throws fewer picks than Aaron Rodgers. However, there is such a thing as being too careful with the ball, and I suspect that Aaron is falling victim to the same kind of thinking as did Zack Greinke. It’s easy enough for a QB go an entire season without a pick by simply throwing the ball directly into the ground on every snap. Your offense won’t be very effective, but it will be “safe,” and Rodgers does a version of this on his many, many throwaways and third-down sacks. Avoiding interceptions should not be an end unto itself. The mark of a great quarterback is the ability to execute all types of plays and use the entire field while limiting mistakes; it is not to take out all possible risks to limit mistakes.

When Rodgers was at his best he was still very careful with the ball, but he also made big plays look routine and threw a huge variety of passes. He didn’t throw interceptions because he was insanely accurate and had one of the NFL’s best arms, not because he was a bit of a chicken. Rodgers still rates fairly well in stats like ANY/A that reward a lack of picks, but I suspect this is a bit like Greinke fooling FIP but not ERA.

AY/A Value for NFL quarterbacks with 100+ passes pic.twitter.com/592q5FdkXt — Justis Mosqueda (@JuMosq) December 3, 2018

The narc on Rodgers this season is his completion percentage, which is one of the worst in football. Completion percentage isn’t everything, but in this case it is telling. Just as Greinke traded walks for harder hit balls, Rodgers is trading completions for fewer picks, and given the sacks he’s taken, that completion percentage probably understates things.

Rodgers has, since 2015, given up a lot of what once made him great. When he holds the ball for a long time we often see it as Rodgers waiting for the big play, but I don’t think that’s right. I think it’s more about ensuring he doesn’t make the big mistake. Rodgers is now defined by that interception streak more than is healthy. He is supposed to be defined by brilliance that just happens to include care of the football as the icing on the cake. An overly careful Aaron is both ineffective and boring to watch, and if he doesn’t realize why interceptions are actually worth avoiding, the Packers dynasty is as good as over.