Miguel Gonzalez Wasn't A Disappointment This Year

Miguel Gonzalez.

Yeah, Miguel Gonzalez.

No pitcher was more widely discussed this year than he. Why? Because he outperformed his FIP to an incredible degree last year, leading to a career-best ERA for a division-winning team, only to follow that up with a stinker of a season marked by a 4.91 ERA. Thus, to many Orioles fans, Gonzalez's 2015 was a disappointment, even despite the slight league-wide uptick in offense. The narrative therefore is that Gonzalez struggled this year and every start became a when-will-he-implode bated breath marathon for Orioles fans, press, and (probably) players.

But this narrative is false. Miguel Gonzalez was basically the same pitcher this year as he was last year. In fact he may have even be a little bit better than he was in the Orioles’ 96-win division championship in 2014. How can this be possible? After all, as I wrote above, his ERA jumped by 1.68 runs per nine innings, which is quite a lot over the course of a season. In his 144.2 innings pitched that's an extra 27 runs crossing the plate, or nearly three whole wins, versus if he had put up the same ERA from last year.

Sure, you may say, but Gonzalez pitches in an offense-friendly park and against better hitters than pitchers in the NL. I agree with you. So let’s look at ERA-, which is his ERA adjusted for park and league and compared to the average pitcher, and where 100 is average and lower is better. (Note that ERA- is different from ERA+.)

• 2014: 82
• 2015: 119

Even if you believe Gonzalez should be given credit for pitching a lot in offense-friendly OPACY, it sure looks like his ability to prevent runs took a huge hit compared to last year. He must be broken.

But other numbers tell a different story. Taking a look at Gonzalez’s FIP, we start to see some idea of why his 2014-2015 change is closer to "he was the same pitcher" than "break out the pitchforks, let's go on a rampage":

• 2014: 4.89
• 2015: 5.01

If we put all our stock in FIP, then Gonzalez’s 2015 appears to be more similar to his 2014 than if we put all our stock in ERA. Instead of 27 runs worse, by FIP Gonzalez would be only two runs worse than last year. Suddenly, the narrative shifts.

Let's take a slight detour here. Talking about FIP brings me to one area in which Gonzalez improved year-over-year. He increased his strikeout rate by 1 percentage point while raising his walk rate only 0.6 pp. As a result, his K-BB rate increased by 0.4 pp. It was still a not-so-good 9.3% this year, but it tells you that overall Gonzalez fooled more hitters in 2015 than he did in 2014. Yet he is vilified by the fanbase and the press.

The other component of FIP, the main one, is home runs. And here, if we measure by HR/9, Gonzalez performed worse than he did last year:

• 2014: 1.42
• 2015: 1.49

Gonzalez allowed just one fewer home run this year despite throwing about 15 fewer innings. But that’s not the whole story. Home runs also have a component of random variation that the pitcher cannot really influence.

As a pitcher who doesn’t strike out a lot of batters, what you want to concentrate on is limiting fly balls. And Gonzalez actually did that this year. His fly ball rate (per batted ball) dropped from 41.7% to 35.8%. This is especially impressive considered he allowed fewer batted balls overall, as evidenced by his increased strikeout and walk rates.

So he allowed fewer fly balls, but gave up more home runs? How is this possible?

Sabermetric research would say that Gonzalez just got unlucky. Before this year, Gonzalez had allowed 62 dingers on 551 fly balls for a HR/FB rate of 11.3%. That's a touch worse than average, but given that Gonzalez pitches a lot in OPACY, it’s understandable. It certainly isn’t awful or terrible. 

Then came 2015. Gonzalez allowed 24 HR in 160 fly balls for an HR/FB rate of about 15%. That’s quite an increase, but again, sabermetric research shows that pitchers generally can’t control extreme fluctuations in HR/FB rate. This is why the metric xFIP, or expected FIP, is useful. xFIP debits the pitcher only for the number of home runs he would’ve given up if he had done so at a league-average rate, given how many fly balls he allowed. For our purposes here using the average rate is a bit too low, but it’s helpful and illustrative anyway.

If we look at Gonzalez’s xFIP from 2014-2015, it shows he barely changed as a pitcher:

• 2014: 4.46
• 2015: 4.48

Now we're at the heart of the discussion. xFIP shows why 2015 Gonzalez was very, very similar to 2014 Gonzalez. It posits a difference of only 0.3 runs, compared to 2 runs for FIP and 27 for ERA. 0.3 runs is hardly anything at all.

When you account for all the things Gonzalez should be focusing on as a pitcher -- striking out batters and limiting walks and fly balls -- his 2015 was essentially the same as his 2014, instead of the massive disappointment it seemed to be. The runs that crossed the plate while he was on the mound (or after he'd just been yanked) counted on the board and contributed to actual losses in the standings, but Gonzalez shouldn’t shoulder all the blame for them. He did what he was supposed to do.

There’s a footnote to this story, and for folks like Dan Duquette who are trying to build a contending team, it’s a happy one. While Gonzalez was busy being same ol’ same ol’, the entire league got worse around him. This means that Gonzalez suddenly looks a lot better compared to other arms that could be on the hill for the Orioles.

To see this trend we can look at xFIP-, which adjusts xFIP for park and league while comparing to the average pitcher. Here are Gonzalez's numbers:

• 2014: 118 (18% worse than league average)
• 2015: 111 (11% worse than league average)

The year-over-year decrease shows that Gonzalez got better (closer to the average of 100) compared to everyone else. This improvement may be cold comfort to Orioles fans this year because the team isn’t measured in the standings by such relative metrics. And Gonzalez is still not a good pitcher, nor even a league-average one. But for fans looking ahead to 2016, hopefully they are less angry when considering Gonzalez as a part of the team’s plans.

All data for this post taken from FanGraphs.