Should We Be Concerned About Jake Arrieta's Early-Season Struggles?

Jake Arrieta has had his problems in 2017, but he may be better than the numbers indicate.

Jake Arrieta hasn't looked like himself through seven starts, which has spanned 38.2 innings. After his outstanding campaigns the last couple years, it's something we're not used to seeing.

He still has a 4-2 record, but it comes with an ugly 5.35 ERA. After throwing six scoreless innings in his 2017 debut, he's allowed at least three earned runs in each start since. That streak was recently topped off by a rough performance against the Colorado Rockies, where he allowed 9 runs (5 earned) in 3.2 innings.

While it's unlikely he's reverted back to his pre-Cub struggles -- remember when he was a mediocre-at-best starting pitcher in a Baltimore Orioles uniform? -- he's definitely regressed.

Or has he? Maybe he's fallen victim to the Chicago Cubs' wave of post-World Series malaise. The numbers tell us that it's a combination of both.

The Bad

There are some legitimate red flags. So far in the young season, the biggest concern with Arrieta is his velocity.

The right-hander's pitch speeds are down across the board, according to the PITCHf/x data on FanGraphs. Velocity is not everything, of course -- he's never been Noah Syndergaard and has still done pretty well for himself -- but a pitcher can make a mistake and get away with it at 94 miles per hour. At 91, not so much.

Year Fastball Sinker Curveball Slider Changeup
2014 93.4 93.5 79.1 89.3 87
2015 94.4 94.6 80.7 90.3 88.7
2016 93.6 93.8 80.6 89.2 88.6
2017 91.7 92.1 77.9 87.1 87.3

Another issue is the kind of contact he's allowed. As a sinkerballer, most of his outs come on ground balls -- his ground-ball rate was 49.2% in 2014 before rising above 50.0% in both 2015 (56.2%) and 2016 (52.6%). But so far this year, it's only 38.9%.

His fly-ball rate, which has never been higher than 28.4% (which happened in 2014), is up to 37.2% this season. His hard-hit rate is also up to 31.0%, which is well above his previous Cubs-high of 25.2% last season. His home-run-to-fly-ball ratio is up to 14.3%, and while that doesn't sniff the top of the leader boards, it's significantly higher than his career 10.4% mark.

So, he's throwing slower, giving up hard contact more often and allowing more homers and fly balls than ever before. He's also been worth just a -0.49 WPA (win probability added) and has earned a 0.7 fWAR. Despite all this, there is some good this season, though you have to dig for it.

The Good

Don't sweat too much, Cubs fans. There are some signs showing that Arrieta has been better than his numbers suggest.

Year FIP xFIP SIERA Strikeout rate Walk rate
2014 2.26 2.73 2.83 27.2% 6.7%
2015 2.35 2.61 2.75 27.1% 5.5%
2016 3.52 3.68 3.94 23.9% 9.6%
2017 3.78 3.57 3.52 25.9% 7.1%

This season's digits don't look much different than those of the previous three years. His xFIP, SIERA, strikeout and walk rates are all better than his 2016 campaign, when he was undeniably a top-tier pitcher. While being nearly unhittable may be a thing of the past, he's still a way above-average pitcher and is unlikely to finish the first half with his current 5.00-plus ERA.

There are other factors showing how his season might just be a case of bad luck. His strand rate (LOB%) is down to 58.5%, which would be the second lowest of his entire career. The lowest came in 2012, before he became Jake Arrieta.

Since his transformation into an oftentimes untouchable pitching cyborg, Arrieta has never had an LOB% below 74.2%. That is an incredible drop off, and unlikely to stay at that poor a level. His BABIP had ballooned to .364 -- it has never been above .320, even during his Baltimore tenure. It's highly unlikely that a career .270 BABIP pitcher will suddenly put in a .364 BABIP, although he needs to start limiting the hard contact again to help this take a dive back to his career norms.

He also still rocks an awesome curveball that clocks in an average spin rate of 2,697 revolutions per minute, good for 18th best in baseball.

The Verdict

The increased fly balls, the decreased ground balls, and most importantly, his diminished velocity are all more than a little concerning. Despite that, all of Arrieta's underlying statistics are positive -- they look nearly identical to 2016, which was way above the average contribution for a starting pitcher.

Bad luck and regression could be cited for his rough start to 2017. His high ERA looks like unlucky noise, and while he's not the elite ground-ball pitcher he once was, he still has an above-average FIP, xFIP, and SIERA, plus some solid strikeout and walk rates.

Jake Arrieta might be on a physical downswing -- especially after three years of a heavy workload -- but there shouldn't be a high level of concern about his slow start just yet.