Armstrong, 27, worked to a 4.38 ERA with 7.3 K/9 and 3.6 BB/9 in his 24 2/3 MLB innings in the 2017 season. That said, he has averaged around 94 mph with his fastball in the majors and has a lifetime 11.3% swinging-strike rate in 43 1/3 total innings at the game’s highest level.
There’s a broader minor-league sample to consider as well. Armstrong posted better numbers in 2017 at Triple-A, where he racked up 11.1 K/9 against 3.4 BB/9 over 29 1/3 frames of 3.07 ERA ball. And he had set down 152 batters on strikes in 98 2/3 innings at Triple-A across two prior campaigns.