(Paul Sancya/AP)

Jackson’s night quickly unraveled, as he walked two consecutive batters then allowed a one-out single. His night ended there, at 64 pitches and five outs shy of his five-inning target. Jackson allowed four runs, two earned, on five hits and those two walks in the Nationals’ 6-3 loss to the Tigers, his worst line in three starts.

Still, Jackson expressed satisfaction with how he felt, and he insisted the sudden control problems that surfaced in the fourth had nothing to do with the adjustments he is making to his delivery.

“I wasn’t really thinking mechanics, if that’s what you’re trying to get to,” Jackson said. “I know mechanics have been my whole thing in spring training. But, I mean, it could be the smallest thing. I just have to come out and just continue to throw strikes.”

The Nationals have told Jackson not to worry about his mechanics, to just throw it to the catcher’s mitt. After his start Tuesday, he seemed intent on convincing himself he had followed that directive. “At this point, if you’re thinking, it’s not really fun if you’re up there trying to think about what’s going on,” Jackson said. “Walks happen. You just have come out and pound the strike zone.”

Jackson should have cruised through an easy 1-2-3 first inning, which included Andy Dirks striking out swinging at a slider. But with two outs, Jason Michaels lost a can of corn in the setting sun. Up came Ryan Raburn, who naturally crushed an inside fastball over the left field fence.

Jackson gave up another run in the third on three singles, none of which were particularly hard hit. He threw a bushel of sliders but no curveballs, and he a good amount of swing-and-misses with the slider.

“It’s the best I’ve felt,” Jackson said. “The results not necessarily the best but it’s spring training. We get caught up in results in spring training when spring training is a time when you’re getting ready for the season. That’s what we’re out here doing. So I’m not going to go kill myself.”