Jake Arrieta owners are starting to panic. The guy who put together one of the greatest half seasons from a starting pitcher in major league baseball history in 2015 and who they were relying on as an ace or #2 starter has struggle out of the gate with a 5.35 ERA and a 1.47 WHIP. Should Arrieta’s fantasy owners be concerned?
Yes and no. Arrieta’s skills in 2017 are actually better than in 2016, when he struggled with control (3.47 BB/9 on 9.6% BB%) and saw his strikeouts fall to 8.67 K/9 (23.9% K%). In 2017, his strikeout rate has rebounded to a strong 10.27 K/9, which is supported by a 25.9% K%, and his walk rate has fallen as well, down to 2.79 BB/9 (7.1% BB%).
The strikeout rate may be a little elevated, since his swinging strike rate and contact rate are almost unchanged from last season (curiously, his contact rate outside the zone has gone up by 7.4% while his in-zone contact rate has dropped by 3.7%). He is throwing the ball in the zone more, so the better walk rate should hold up.
Where Arietta has been hurt, like so many pitchers the past couple years, is giving up the long ball. Arrieta has been great at limiting home runs in past season, including a 0.73 HR/9 in 2016. That number has jumped up to 1.40 HR/9 thus far in 2017.
The good news is that it doesn’t look deserved, since the six home runs he’s allowed come on 4.0 xHR, pointing to a lack of luck on some fly balls that wouldn’t normally leave the yard. While Arietta’s hard hit rate has increased, his soft hit rate has as well. Among starting pitchers with 100 or more batted ball events in 2017, he ranks sixth best at suppressing exit velocity (84.6 mph) overall and tops the league in lowest exit velocity on fly balls and line drives at 89.4 mph and is middle of the pack just on fly balls (88.8 mph).
The bad news is that his fly ball rate is up 9.3%, leaving him more susceptible to the long ball. In other words, even with the same low HR/FB rate as past seasons (4.5%, 7.8% and 11.1% the past three seasons, respectively), he would still give up more home runs in 2017.
Arrieta has thrived the past few seasons using his sinker to generate ground balls, but his ground ball rate has dropped 13.7% in 2017, including a 10.8% drop on his sinker. The result is a .512 slugging percentage against the pitch, including 3 home runs. Arrieta’s trademark pitch is not doing its job, which should worry his fantasy owners.
The hard part in predicting what’s next for Arrieta is the sharp drop in his velocity this season. As Jeff Zimmerman at Fangraphs.com points out in his pitch velocity tracker, Arrieta has seen a 2.7 mph drop in his sinker’s velocity, which may be the reason that hitters are now able to square it up a bit more. If the velocity does not return, it’s hard to see him regaining his status as an ace.
Should fantasy owners be worried about Jake Arrieta? Yes and no. A lot of the underlying skills point toward some bad luck on batted balls, particularly on fly balls. A strikeout rate at around a strikeout per inning is very useful and Arrieta’s control problems from last season look to be getting better. But the loss of velocity on the sinker, his trademark pitch and one he’s throwing on one out of every two pitches this year (50.2%), makes it hard to see a return to greatness.
As a result, my best guess is that we see Arrieta’s luck even out over the course of the season and that he settles in as a very useful #2 or #3 fantasy pitcher with an ERA around 3.50 and a WHIP around 1.15 with a strikeout per inning. Not what fantasy owners were hoping for or expecting this season, but a very serviceable member on fantasy teams.