The knee strain that has kept Rangers right-hander Doug Fister on the disabled list since mid-June will prove to be season-ending, reports Gerry Fraley of the Dallas Morning News (Twitter link). Fister’s knee hasn’t responded well to the rehab efforts, and he won’t pitch again in 2018.

Fister, 34, signed a one-year deal worth $4MM to join the Rangers this offseason. That pact comes with a $4.5MM option for the 2019 season as well, so it’s not a guarantee that the injury will ultimately end his tenure with the organization. The Texas front office will owe him a $500K buyout of the option regardless, so it’ll boil down to another $4MM decision on their end. Given his recent track record, it seems likelier to be declined, but the Rangers organization is also perilously thin on rotation depth.

While Fister didn’t pitch especially well in Texas, he did give the Rangers a dozen serviceable starts. In 66 innings, the veteran worked to a 4.50 ERA with 40 strikeouts against 19 walks to go along with a 50.6 percent ground-ball rate. His fastball, though, sat at an average of 88.4 mph — down from last year’s 89.8 mph mark — and Fister’s 5.1 percent swinging-strike rate was not only the second-worst mark of his career but also the lowest mark of any pitcher in MLB with at least 60 innings thrown.

It’s been nearly a half decade since Fister, once one of the game’s more underrated hurlers, was an above-average contributor in a rotation. He tossed 164 innings of 2.41 ERA ball for the Nationals in 2014 but struggled in 2015 and ultimately lost his rotation spot with the Nats. Since that time, he’s seen his fastball velocity drop substantially, bottoming out at 86.2 mph in 2015 before rebounding to some extent over the past two seasons. He’s struggled to a 4.68 ERA with a near-identical 4.64 FIP across the past three seasons between the Astros, Red Sox and Rangers.