Tanner Roark. (Photo by John McDonnell/The Washington Post)

The Nationals will announce their fifth-starter decision Saturday, and they have revealed few clues whether Tanner Roark or Taylor Jordan will join their rotation. The decision may well not be finalized yet. Any attempt to divine the answer is speculation.

But that doesn’t mean we can’t speculate: The best guess is Roark. Four reasons, based on both observations and conversations with Nationals personnel:

1. It would be difficult for the Nationals to tell a pitcher who went 7-1 with a 1.51 ERA, and never faltered thereafter, to go back to the minors. Roark proved himself last season and, through his performance this spring, proved he at least belonged in the majors, at least as a reliever. Once the Nationals determined Aaron Barrett would be the final member of their bullpen, it only boosted Roark’s cause.

2. Minor league seasoning would do more for Jordan than it would for Roark. Roark is 27 and has thrown 582 2/3 innings at Class AA or higher – he knows what he’s doing. Jordan is 25 and, because he lost a year to Tommy John surgery, has thrown 142 innings above Class Low-A. Even Jordan saw the logic in that.

“I’m just going to play it by ear,” Jordan said after his last start. “I’m happy to go to Triple-A. It’s still a bump up for me. I’ve never even been to Triple-A. Last year was just a blessing to be up in the big leagues. I don’t expect anything.”

3. Roark earned trust from both teammates and decision-makers at a crucial time. Jordan made nine starts as the Nationals floundered their way through midsummer. Roark jointed the Nationals, and in many ways propelled them, as they surged to the fringes of playoff contention. He never flinched.

This type of argument for Roark should not be taken as an argument against Jordan. The Nationals believe in him, too, and he impressed with a 3.66 ERA in his big league cameo. Peppering the strike zone with his sinker, Jordan allowed three homers and 11 walks in 51 2/3 innings. He’s good. The Nationals would be happy to put him in their rotation. Still, no matter how small their respective samples, he hasn’t done what Roark has done.

4. Both will pitch Saturday. Roark, Matt Williams said, will start the game. Trying to read into that might be folly. It could be stupid. But do you think they flipped a coin?