SEATTLE – Byron Buxton warily eyed the timing mechanisms, set up by the Twins' training staff, as he went through his stretching program in short left field Wednesday. When he felt ready, the center fielder stood along the foul line, waited for a pause in batting practice, and began running as the trainers and manager Rocco Baldelli looked on.

Four more times Buxton repeated the test, gradually running a little faster. But in each of the last two, he appeared to try to run at full speed — then slowed to a jog after about 40 feet.

If he's fully healthy, now six weeks after suffering a severe hip sprain, Buxton didn't appear able to prove it Wednesday. And that makes it extremely doubtful that he will play in Texas this weekend. In fact, it makes it far more likely that he will play again for the St. Paul Saints, on another rehab assignment, before he plays again for the Twins.

"He may play more rehab games — that's not definite, but it's certainly a possibility," Baldelli said before Buxton's workout. "He's feeling pretty good, but we need to get him to the point where he's not just doing pretty good, but where there are no more acute issues he's dealing with."

Buxton went 5-for-9 during three games in St. Paul last week, with a double, triple and two home runs. But he wasn't as healthy as he appeared, Baldelli said.

"He felt something in the first game. He felt something trying to go down the line. Obviously it didn't feel good, and is related to the issue he's been dealing with," the manager said. "He did feel something that's going to keep him out and now we have to build him back up."

Buxton appeared frustrated as he walked off the T-Mobile Park outfield, and he said simply, "Great!" when asked how he felt. But it was clear that he had not run well enough for that to be true.

"He's been in my office multiple times, trying to talk his way into just jumping right back in and playing," Baldelli said. "But when we get down to the details and exactly how he's doing, it's not quite time yet."

Baldelli acknowledged that bringing Buxton to Seattle gave the impression that his return was imminent, but he said a conversation they had over the weekend convinced him that that was unlikely, and in fact, that he needed a few more days off.

"Getting back on the baseball schedule with his teammates, going through full days, not just working out on his own back in Minneapolis, it would be good for him to get into that routine," Baldelli said. "It's simple. When Buck can run, he's going to play. And if he's inhibited — frankly, if I think he's going out there and putting himself at risk by sprinting of reinjuring himself — then he's not going to play."

Kepler nears return

One starting outfielder does figure to play on Friday in Texas. Max Kepler, out since May 30 because of a strained left hamstring, was scheduled to play the outfield for the Saints on Wednesday, and if he has no problems, could meet the team in Arlington.

His addition will force decisions about both the roster and the lineup. Gilberto Celestino or Nick Gordon figures to be optioned to make room for Kepler; Celestino probably needs more minor league time than Gordon, but the latter has played the outfield for only a week. And if the Twins don't want Kepler to play center field for fear of aggravating the hamstring, Baldelli will have to decide which rookie loses playing time — Alex Kirilloff or Trevor Larnach, who have played well as corner outfielders.

Jax optioned

The Twins made one other roster move official: Griffin Jax — who threw 93 pitches Tuesday, most by a Twins reliever in five years — was optioned back to St. Paul. Caleb Thielbar, recovered from a strained left groin, was activated, giving the Twins two lefthanders in the bullpen once again.