#15. Jake Arrieta, Chicago Cubs
2015 WAR: 8.7
2014 WAR: 5.3
WAR Improvement: 3.4
It’s by no means a knock on Jake Arrieta to suggest he’s going to have difficulty replicating the 8.7 WAR he posted in 2015.
That mark has only been matched or exceeded by five pitchers this millennium: Zack Greinke, Roy Halladay, Randy Johnson, Pedro Martinez and Curt Schilling. Only Greinke, Johnson, and Schilling have done so in multiple seasons.
Plenty of the big names have fallen just shy. Clayton Kershaw, for all the hype he gets about being one of the all-time greats, topped out at 7.8 WAR in 2013. Justin Verlander (8.4 WAR), Johan Santana (8.6), Tim Lincecum (7.9), CC Sabathia (7.5), Felix Hernandez (7.1) and Cliff Lee (8.6) have all seen their best seasons come up short as well.
Could Arrieta join the multi-season club? He’s talented enough to, and he’ll almost certainly find himself in the Cy Young conversation once more.
But avoiding even the tiniest bit of regression will prove nearly impossible, especially since he benefitted from an unsustainably low BABIP, leaving 80 percent of runners on base (career average of 71.2 percent) and a HR/FB below his lifetime mark while making 33 starts.