With the large stable of pitchers available for the Orioles, not much is dependent on Jake Arrieta pitching in a meaningful role for the team in 2013. He was once a premier prospect in the Orioles organization with his advanced fastball and a promising curveball. Once you reach that status of being a high ceiling prospect, a lot of dreams get placed on that arm and those dreams can be difficult to let go. Those dreams appeared to be hiding underneath the surface last year as Jake cut his walks and increased his strikeouts. He was a darling of those who are sabremetrically-inclined last year because his ERA was two and a half runs greater than his xFIP and SIERA (3.65 and 3.59, respectively).
The expectation from that point of view is that his future performance is more likely to be closer to the advanced pitching metrics than traditional ERA. Briefly put, xFIP looks at events where the pitcher has complete control (strike outs, walks, and home runs) as well as conversion for park factors (e.g., Camden Yards is a little home run happy). SIERA looks at how walks, strikeouts, ground balls, and fly balls characterize a pitcher. These peripherals have been shown to be more predictive of future performance than simply using a descriptive statistic like ERA.
Anyway, the sabermetric perspective is one that says Arrieta was unlucky last year. Much of his trouble came from him being hit incredibly hard, generating a high line drive percentage that was uncharacteristic of his career to date. This initially appears to be a concern, but there has been little evidence showing that line drive percentage carries over from one year to the next. That this poor performance has not be observed in seasons past, suggests that we should not expect it going forward. Line drives, of course, are a major reason why xFIP and SIERA discount Arrieta’s ERA. As they both shrug at line drives, line drives are very effective batted balls as 73%, on average, wind up as being base hits with a good many of them going for extra bases. In comparison, 24% of groundballs work their way out of the infield for almost exclusively singles and 15% of fly balls hit the ground with some leading to extra bases, including a good number landing somewhere past the outfield fence. Back to the point, these tools tend to say that we should be seeing a rather effective Jake Arrieta next year.
I agree, to an extent. I think Arrieta was unlucky last season with batted balls and simple linear patterns of play development. By that I mean, he tended to be quite unlucky for having bad events group together. However, my view is tempered by a couple things. One, as much as line drives are not predictable from one year to the next, I think that may not exactly be the case for Arrieta. Last year, he pitched differently than in years past. When falling behind in the count, Arrieta walked 18% of those batters which differed from 29% in 2011. A major reason why his walk total decreased so much (thus, lowering his xFIP and SIERA) was that he became more aggressive with the hitters. That resulted in hitters not really improving their OPS (974 vs 989), but a major difference in batting average (312 vs 261). As you can imagine, a successful batted ball is more dangerous than a walk.
Second, I have long standing concerns about Arrieta’s ability to pitch to left handed batters. This is not a new concern. It is something that has been hanging on Arrieta for quite a while. In our prospect previews over at Camden Depot, one of my major issues with Arrieta in the minors is that he has a horrible time putting left handers away. His pitching strategy is basically getting into counts where he can effectively use his curveball, a pitch that is highly ineffective against the lefties he faces. This results in the handed wOBA splits we see each year (2010- 389/276; 2011 – 373/316; 2012 – 359/295). In other words, Arrieta consistently makes lefties look like a top 15 batter (e.g., Robinson Cano) and righties look like a bottom 15 batter (e.g., Jeff Francoeur).
That handed split is a major problem. Teams can prepare for starters. Last year, Arrieta faced a lefty 54% of the time, which is also about the same rate as fellow right handers Jason Hammel and Miguel Gonzalez. The difference is that Hammel ate up lefties last year (262 wOBA) and MiGo was not too shabby as well (308 wOBA). They both can handle the extra lefties, Arrieta cannot and has shown throughout his career that this is the case. Teams will challenge Arrieta with lefties and he may decide to continue challenging them and get crushed. Or, he may decide to nibble more like he used to, increase his walk rate, and being a serviceable fifth starter like he was.
To me, this situation is similar to pyrite, Fool’s Gold. Among other minor leaguers, Arrieta looks impressive. His stuff plays well and many of his troubles could be explained away with youth. In the Major Leagues, those troubles have grown more visible and, with experience, it appears that his pitches are never going to be effective against left handed batters. In other words, his value looked much more than it wound up being when you compared him side-by-side with genuinely valuable talent. Similar to how unimpressive pyrite appears when sitting next to actual gold.
However, this perspective is unfair to both pyrite and Jake Arrieta. Pyrite is very useful in the industrial manufacture of sulfuric acid and used in many applications. Jake Arrieta is quite excellent at getting right handers out. I imagine every pitcher would love the opportunity to face Jeff Francouer over and over and over again. The value here is that Arrieta is truly a late inning relief arm. He is a pitcher who can be slated into the 7th or 8th to cut down same handed batters while working around the left handers. Yes, Jake Arrieta is pyrite and, for that, we should be thankful.