Armstrong has been sidelined during camp with a neck injury, Marc Topkin of the Tampa Bay Times reports.
It's unclear how severe the injury is. The right-hander was a key contributor to the Rays bullpen in 2022 with a 3.60 ERA and 1.27 WHIP, and he agreed to a one-year, $1.2 million deal to avoid arbitration last month. If healthy, he should be a middle-relief or set-up option for Tampa Bay in 2023.