ST. PETERSBURG -- Saturday night was about evaluating Miguel Castro while taking his first career big league start with a grain of salt. Good or bad, Orioles manager Buck Showalter stressed Saturday afternoon, the outcome was not going to be a definitive evaluation of what the righty could be for the O's come spring.
Still, Castro held his own in the 4-3 loss to the Rays, working out of several early jams before surrendering a three-run homer to Brad Miller in the fourth. His final line of 3 1/3 innings included six hits and a walk, with three strikeouts and a wild pitch in the 59-pitch outing.
"He got a little tired," Showalter said. "He worked through a lot of trouble. It wasn't like it was an unscathed first three innings. It was a good step for him. We'll see if he can build on it, give us some options as he goes forward."
After a 1-2-3 first, Castro used his defense to wiggle out of a one-out single and double in the second inning with a key fielder's choice cutting down the runner at home. He had runners at first and third in the third inning, but struck out Wilson Ramos and got Logan Morrison to fly out to escape that jam.

"Overall, [I'm] happy for the opportunity," Castro said through interpreter Ramon Alarcon. "It's been a long season, many different experiences. Happy to be out there, healthy and just trying to compete."
Castro, who entered the game 3-2 with a 3.29 ERA in a career-high 38 outings, last pitched Sept. 22 and said that the long layoff was the biggest adjustment to making the start. After Miller took him deep on a 2-2 pitch that scored three, Castro exited one out later following a comebacker.
"He was making really good pitches, commanding all three of his pitches. Overall, he did really well, I thought," said rookie catcher Chance Sisco. "[There was] one pitch that he kind of left up, and that's what cost him the runs. But other than that, he made really good pitches. Smooth throughout the three-plus innings that he went."
Castro, acquired in an April trade with Colorado, has impressed the O's with his performance on the field and his makeup. Showalter liked that Castro didn't act much different leading up to the start, though there are still some growing pains.
"He's a pretty under-control guy. He likes to compete. He's a smart guy. He knows what's going on and we certainly don't draw a lot of attention to it for him," Showalter said. "It's little things, like times to the plate. He fluctuates all over the place. It's something that he's got to do a better job with."
For Castro, this season has been a huge learning experience. Unsure if he'll pitch in winter ball or just rest until Spring Training, the righty will take some important lessons with him heading into 2018.
"I take, 'Keep your head up, don't give up, go out there and try to compete, regardless of the results,'" he said. "Sometimes the results are not going to be what you want them to be, so go out and keep your head up."