There are injury concerns whenever a pitcher displays a drop in velocity, but Bailey Ober has identified why he's had a downtick over his past two starts.

His pitching mechanics, he said, are "not smooth and disjointed."

When the Twins righthander pitched Friday against Toronto, yielding five runs in seven innings, he blamed his dip in velocity for his troubles the second and third time through the batting order. Ober threw 14 fastballs across the first three innings and nine were above 90 mph. In the past four innings, none of his 19 fastballs topped 89.6 mph.

"I'm trying to work on that," said Ober, who is averaging 90.4 mph on his fastball this season, down from 91.7 mph last year. "I've been putting a lot of time in and work throughout the weeks, especially after my previous start in Seattle where it really ticked down."

Ober's issues with his velocity, and his mechanics, date to spring training. He threw four fastballs Friday below 88 mph and the lower velocity, he says, erases his margin for error against hitters.

"I was able to figure it out for a little while at the beginning of the season, up until mainly the last two or three starts," Ober said. "When something is off, you revert back to the way you were throwing, and that's unfortunately the way I've been throwing. It hasn't been the most efficient movement wise. That's why we're seeing the lower velos. Just trying to work through it and stay healthy."

Ober, despite battling his pitching mechanics, owns a 2.85 ERA over his past 12 starts. But he hasn't struck out more than four batters in any of his past five starts, and he gave up three homers in his past two outings.

Eventually, Ober hopes muscle memory from all his work between starts will benefit him when he's pitching deep into a game.

"The first couple innings, I don't have to think about it," he said. "Then you get a little stiff, which is normal throughout a game. When I'm getting stiff right now, I feel a bigger change than what I normally do with my mechanics. Whenever I start to feel that, I know even before I look at the radar that it's probably going to be a little bit lower.

"There are some times where I'll throw one, it'll be decent velo and I'll be fine. Then the next pitch, I'll try to get a little bit more and then it actually tends to go down when I'm trying to get more velo."

Coulombe nearing return

Twins lefthander Danny Coulombe pitched a scoreless inning during his rehab assignment with the Class AAA St. Paul Saints on Friday, retiring the three batters he faced on nine pitches.

"Felt good, I just wanted to see some hitters," said Coulombe, who threw two bullpen sessions before his rehab outing. He said most of his discomfort was in his biceps, not his forearm, but he hasn't felt it since he started throwing again. "I like where I'm at right now."

Twins manager Rocco Baldelli didn't give a timetable for Coulombe to return, except to say, "We could get him back very soon." The Twins are currently without a lefty in their bullpen.

Etc.

• Twins closer Jhoan Duran drew a brief visit from a trainer in the ninth inning Saturday after he slipped on the mound following a pitch. "When I landed, there is a big hole over there," Duran said. "When I put my foot in, I slipped a little bit, but I'm fine."

• George Springer became the 13th visiting player to reach double digits in home runs at Target Field with his go-ahead, two-run homer in the eighth inning Saturday. Weirdly, among those 13, he's the fifth to homer there as a member of the Blue Jays, more than any other team. The other four are Edwin Encarnacion, Jose Bautista, Josh Donaldson and Kendrys Morales.

• Michael Tonkin, the 35-year-old reliever who has yet to pitch in the big leagues this year, issued a walk and gave up a hit as he began his second rehab assignment with the Saints. He made six relief appearances on a previous rehab assignment before he was shut down because of tendinitis in his right biceps, and he received two cortisone shots.