Jake Arrieta started his big league career in 2010 amidst lots of hype. For nearly four years he toiled in anonymity. That's actually not strong enough. He actually just stunk. There, I said it. For four years he was terrible. Last season it all turned around for Arrieta as he dominated batters at an elite level for 25 outings. Now comes the hard part. What will he do for an encore?
THE MINORS
2008: As a 22 year old rookie in pro ball, Arrieta went 6-5 with a 2.87 ERA and 1.16 WHIP over 113 innings. He struck out 120 batters.
2009: Ranked as the 67th best prospect in baseball according to Baseball America. Baseball Prospectus had him 52nd. Appeared at Double and Triple-A making 28 starts. Went 11-11 with a 3.40 ERA and 1.31 WHIP an a 8.8 K/9 mark.
2010: Ranked as the 99th best prospect in baseball according to Baseball America. Baseball Prospectus had him 70th. Made 11 starts and 12 appearances with a 6-2 record, 1.85 ERA, 1.12 WHIP and 64 Ks in 73 innings.
2012: Made 10 starts with a 4.02 ERA and 1.32 WHIP at Triple-A. He walked 4.5 batters per nine innings.
2013: In 16 outings at Triple-A, 15 starts, he went 7-5 with a 4.08 ERA, 1.35 WHIP an a 8.7 K/9 mark.
2014: Made five starts at High-A and Double-A going 1-1 with a 2.25 ERA and 1.00 WHIP.
TOTALS: 36-28, 3.18 ERA, 1.24 WHIP, 8.8 K/9, 2.34 K/BB over 492 innings
THE MAJORS
2010: As an Oriole rookie he made 18 starts with moderate results. OK, with poor results. He went 6-6 with a 4.66 ERA, 1.53 WHIP an a pathetic 4.66 K/9 mark.
2011: Won 10 games in 22 starts but was saddled with a 5.05 ERA, 1.46 WHIP an a 1.58 K/BB ratio over 119.1 innings.
2012: Posted a strong 8.56 K/0 mark and a then career best 2.75 BB/9 mark. Don't look at the record (3-9) or ERA (6.20) though. They were ghastly.
2013: Pitched for the Orioles and Cubs over 14 games. Went 5-4 with a 4.78 ERA, 1.33 WHIP, a career worst 4.9 BB/9 mark leading to a 1.46 K/BB ratio over 75.1 innings.
2014: Bonkers good. Arrieta went 10-5 with a 2.53 ERA and 0.99 WHIP. He also struck out 167 batters in 156.2 innings and only walked 41 guys leading to a 4.07 K/BB ratio for the Cubs.
THE SKILLS
Dude is already 28 years old. In fact, he will be 29 in March. It's obviously not unheard of for a pitcher of that age to take the next step, but I just wanted to be sure you understood that this wasn't some breakout effort by a 23 year old. Arrieta has been around for a long while.
Going back at his minor league work it's easy to see why he was looked at as one of the better pitching prospect in baseball. At the same time, that minor league success was years ago. Honestly, the last time he was something of note in the minors was back in 2010. That's a while ago ain't it? Arrieta has racked up 481 Ks in 492 minor league innings, an obviously that's nearly one an inning. However, the strikeouts came with a price - walks. Arrieta walked 3.8 batters per nine innings in his minor league career, and to review, the big league average last season was about 2.9. Arrieta was well off that pace in the minors. Flash forward to the big leagues and Arrieta was a walk machine. Over his first four big league seasons he walked 4.02 batters per nine innings, an awful number.
So let's review.
Over six minor league seasons he walked 3.8 batters nine innings.
Over his first four big league seasons he walked 4.0 batters per nine innings.
In 2014 he walked 2.36 batters per nine innings.
Which number is the outlier? Do you believe in six years of data or do you believe in five months, and make no mistake here, they were drastically different results.
During six minor league seasons he nearly struck out a batter per game at 8.8 per nine.
During his first four big league seasons he struck out 6.90 batters per nine.
In 2014 he struck out 9.59 batters per nine innings.
Which number is the outlier?
Oh, and his swinging strike percentage went from seven percent his first four seasons to 10.2 percent in 2014. Sustainable?
And that's really the rub here. Arrieta was a good minor league pitcher. He was a bad major league pitcher. He then went out and pitched like he was Felix Hernandez in 2014. Who does that? Better yet, who does that in back-to-back seasons after being Wade Miley for four years?
Why the major shift in 2014? Some thoughts.
Through four big league seasons Arrieta threw his fastball more than 60 percent of the time each season at a velocity of 93.1 miles an hour. Last season he threw his fastball 47.5 percent of the time at 93.5 mph. Interesting. Arrieta threw his curve ball about 16 percent of the time his first four seasons. Last year he threw it 17.8 percent of the time. Pretty much the same right there.
Arrieta used to throw a slider. I say used to because he pretty much scrapped the pitch in 2014 replacing it with a cutter (the pitches are very close and hard to discern, so depending on the recording system you trust the pitch might still be called a slider). Regardless of what you call the pitch he nearly doubled his use of that hard "off-speed" pitch. Boom goes the dynamite as he threw the pitch 28 percent of the time according to Baseball Info Solutions. It ended up being his best pitch. His fastball produced 13.5 runs above average according to Fangraphs while his slider was up at 15.0.
He also kept the ball down in the zone better than at any point in the past with a 49 percent ground ball ratio in '14 (the mark was 43 percent before last season). That growth came directly from the fly ball column as his league average 34 percent fly ball rate his first four big league seasons dropped to 28.4 percent last year. The result was a 1.73 GB/FB ratio. That mark was in the 1.20's his first four seasons.
Speaking of fly balls, he not only produced the lowest mark if his career, he also kept the ball in the yard with never before seen success. Arrieta had allowed a HR/F ratio of 15.0, 14.5 and 12.3 percent from 2011-13. Last year he cut that mark by two-thirds down to 4.5 percent. (1) A mark under five percent isn't sustainable. (2) Guys don't maintain a rate that is 1/3 of their "normal" consistently, do they? Answer - they don't.
Can the addition of a new pitch explain all that growth?
Arrieta also attacked lefties in a more effective manner. He attacked them by keeping the ball lower in the zone (see the grounders above). The results included a mere .251 wOBA (weighted on base average, which talks about the full game of a player - not just the ability to get on base - and is read just like regular on base percentage) an d a batting average against portsiders under .200. The previous four years the numbers were the following.
2010: .311 average and .389 wOBA
2011: .251 average and .373 wOBA
2012: .287 average and .359 wOBA
2013: .183 average and .297 wOBA
The new approach did wonders for his success, especially against lefties.
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CONCLUSION
So what do you believe? Do you believe that relying more heavily on his cutter/slider explains all the success that Arrieta had last year? Does that focus explain him moving from the ranks of the below league average to the pantheon of the elite? From the tone of this piece you know my answer - it's no. I'm not saying that Arrieta isn't going to have success in 2015. I'm merely pointing out that the overwhelming majority of evidence strongly suggests that Arrieta might have just had the best season of his career, and you certainly don't want to pay full price for that given that you have to cede that I might be correct.
10 team lg: A risky proposition in a league this shallow given the concerns about him holding on to his strikeout and walk numbers from a year ago. This guy still owns a career 2.15 K/BB ratio, a number he nearly doubled last season at 4.07. With the inherent risk in his ratios (ERA and WHIP), he's hard to trust in a league this small.
12 team lg: Am I the only one who is concerned that he's yet to throw 160 big league innings through five seasons? Apparently I might be. Until a guy has done that, and let's face is that's a pretty low bar for a supposed fantasy ace, can you be confident that he will do it? Think long and hard about investing in him as your second, or even third starting pitcher in this format.
15 team lg: Concerns are still weighing on me in this format, such as the fact that in his first four seasons his best ERA was 4.66 and his best WHIP was 1.33. I can't wipe away those worries based on 25 starts last season. Not saying I wouldn't want Arrieta on my roster in this setup, but the fact is that someone else will likely be more bullish than myself and "reach" to make him their SP2. I don't want to be that guy.
NL-only: I know this may not be fair, but I keep thinking Ubaldo Jimenez with Arrieta. Truth be told, prior to 2014 that would have been a bit unfair to Ubaldo. Being that it's hard to fully explain the growth we saw from Arrieta last season, and the fact that the growth took him into the stratosphere, you know what I'm gonna say already, right?