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.
- 2014: 82
- 2015: 119
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
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
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
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)
All data for this post taken from FanGraphs.