There are some things in baseball that are difficult to make sense of when you expect a certain performance out of a player and then the results are well on the opposite end of the spectrum regarding those expectations. Sometimes though, the results versus expectations can be chalked up to bad luck and when it comes to Baltimore Orioles starting pitcher Jake Arrieta I believe he was one of the unluckiest men in baseball last season.
He pitched 114.2 innings in 2012 and posted an ERA/FIP of 6.20/4.05 while also posting the highest strikeout rate of his career, 8.56 K/9, and he managed to cut his walk rate by nearly half from the previous season to 2.75 BB/9. The difference between his actual ERA and then his FIP should be enough to alert you to the fact that there was something amiss in regards to his performance on the field and then the statistics that measured the end results. Add in the increased strikeout rate and falling walk rate and it even further solidifies that thought.
I could probably write a book discussing the counting statistics that try to convince that Arrieta is one of the worst pitchers in baseball, while the peripheral indicators such as BABIP (his was .320, which was
fifth highest 10th highest among pitchers with at least 100 IP last season) and LOB% suggest he was largely unlucky. I could explain to you that when a pitcher manages to raise his strikeout rate and lower his walk rate from one season to the next that you would typically see an increase in overall performance, but this wasn’t the case for Arrieta. I could also talk about how he had surgery to remove bone spurs from his elbow, which ended his 2011 season in August, and that coming back from any type of surgery on your elbow takes some time to fully readjust from.
Instead of going through all of that in great detail though, I instead want to focus on three things: the fact that Arrieta will be just 27 years old heading into this season, he has only pitched a total of 334.1 innings at the major league level over three partial seasons, and then finally – kwERA as a better performance indicator than ERA or FIP.
When it comes to a player’s age it does actually matter. While it’s nice to have someone who can perform at a high level straight out of the minors, or only a short year or two removed from the draft, that’s not typically how it happens though. Many players don’t start hitting their stride until they’ve reached their prime years which usually begins around age 26 or 27 and lasts through their age 29 – 31 seasons. Arrieta is coming into his prime years and he has just enough experience under his belt, at the major league level, that he knows what he needs to and can do this upcoming season.
The fact that he only has 334.1 innings of work at the major league level to his credit lets us know that there is still a good deal of potential and upside in him. It’s difficult to say that what we’ve seen from him up to this point is all he’ll ever be because 334.1 innings is not enough to say with any certainty that his performance won’t improve. Many pitchers don’t really get comfortable at the big league level, hit their stride, or reach their full potential until somewhere around the 500 inning mark.
Even though you’re probably about to get the impression that I’m man-crushing on Glenn DuPaul, here is a bit of research he did on ERA estimators for The Hardball Times and at what point true talent or performance normalizes for pitchers (his research is based on previous research done by Colin Wyers from Baseball Prospectus).
As far as us being able to determine what his actual performance was last year and what we can reasonably expect this upcoming season, if given the chance, I am going to use kwERA. Many people prefer to keep things simple by using ERA as the standard for evaluating a pitcher’s performance or maybe taking things a step further and using FIP. The great thing about kwERA is that it’s actually a bit simpler than both.
All kwERA does is subtract a modified version of walks from strikeouts and then divides by plate appearances, which will then give you a very strong indicator of future ERA performance. The formula is:
kwERA = 5.40 – (12*((K-BB)/PA)))
I’m not going to take credit for any of this though because it is actually the work of GuyM and was then further explored by Tom Tango. The information that I am pulling for this piece about Arrieta is actually made possible by Glenn DuPaul from research he did for Beyond the Box Score. It is his data, which can be found in excel format here, that made this so much easier for me to look at as opposed to having to run the numbers myself. If you get a chance then hit him up on twitter to thank him for his hard work.
From DuPaul’s research this is what he had to say specifically about Arrieta:
For most of these pitchers, all kwERA is really saying is that their ERAs can’t possibly that much worse than the MLB average (4.19 ERA was average for starters) again in 2012, and they’re due for some regression to the mean.
The more interesting names on this list are the ones who are projected (by kwERA) to better than average in 2013, after having an ERA higher than the league average in 2012.
Arrieta, a starter for the Orioles has by far the largest gap among the pitchers on this leaderboard. His 3.65 kwERA ranks 31st ahead of names such as Roy Halladay, Matt Garzaand Anibal Sanchez, while his actual 6.20 ERA ranks 139th out of the 142 pitchers on the leaderboard.
In 2012, both Arrieta’s strikeout rate and his walk rate were better than league average (leading to his above average kwERA), but his batting average on balls in play (.320), home run rate (1.26 per 9) and dreadful strand rate (57.3%) caused his actual ERA to ballon over two and a half runs above what his strikeouts and walks would indicate.
According to kwERA and DuPaul’s research we could expect Arrieta to bounce back from his abysmal 2012 season and perform at something closer to an above average level in 2013. I’ve been fortunate to watch Arrieta pitch a few times in person and I’ve watched a large number of his starts on television and I would agree that he could bounce back reasonably well this season. After all, how could 2013 be any worse for wear performance wise for him than 2012 was?
His strikeout and walk rates suggest to us that his nearly league leading BABIP, among qualified pitchers, and awful strand rate should see modest improvements which would in turn improve statistics such as ERA – which is what the majority of people use to identify whether a pitcher is any good or not. I don’t particularly agree with using ERA as the end-all, be-all in pitcher evaluation but it is one of the more popular metrics available that non-stat heads use and it does alright enough I guess.
My point is that Arrieta ended up being one of the unluckiest men in baseball last season and there is no way something like that is bound to happen to him again. As long as he’s given the opportunity, which I’m sure he will be, then he’ll have his turn to prove that last year was a true anomaly and he’s more than capable of being a reliable major league caliber starting pitcher.