SAN DIEGO -- D-backs left-hander Wade Miley, who allowed four runs on nine hits in five innings while experiencing a drop in velocity on Friday, watched video of the start on Saturday to try to understand why he struggled.
"Mechanics weren't too bad," Miley said. "Might have been rushing, flying open a little bit. Nothing major."
When a pitcher rushes and opens his lead shoulder prematurely, he can end up pushing the ball rather than getting on top of it. That can reduce not only control, but also velocity.
"A lot, because you've got no lower half," Miley said of the result of poor mechanics. "Spinning off means you have no power below. So it's kind of a positive in a way. I just have to get in the bullpen and work on some things."
Among the things he will work on is staying back and staying over the rubber.
Miley will throw his normal between-starts bullpen session on Monday in Los Angeles, and he is slated to start Wednesday's series finale against the Dodgers.
Gregorius returns from concussion
SAN DIEGO -- Shortstop Didi Gregorius was reinstated from the seven-day concussion disabled list before the D-backs' matchup with the Padres on Saturday.
To make room for Gregorius on the 25-man roster, outfielder Alfredo Marte was optioned to Triple-A Reno.
Gregorius was hit in the head by a Josh Outman fastball on April 26 against the Rockies and sustained a mild concussion. He played in extended spring training games on Thursday and Friday at the team's Salt River Fields complex in Scottsdale, Ariz.
Gregorius said he was not worried about getting hit again.
"Not really, I was just trying to get my at-bats, trying to work on everything," Gregorius said. "Things happen in the game that you can't control."
In fact, Gregorius was struck in the leg by a pitch during one of the games.
"It's tough like that because you get pitchers from extended and they don't have the control every time," he said. "Everywhere you go pitchers don't always have the control because it's not easy to pitch. One was a little bit wild, I got hit by a pitch, but that's all right. I stayed in there because I really wanted my at-bats, so they put somebody at first for me and I stayed in and hit."
Marte was hitting .186 in 43 at-bats for the D-backs. He made the team out of Spring Training after injuries caused outfielders Cody Ross and Adam Eaton to start the year on the disabled list.
"He's come a long way, certainly, since we watched him last year," D-backs manager Kirk Gibson said of Marte, who played at Double-A Mobile in 2012. "He had a good spring. With all the injuries, he had a chance to play and make an impression. It'll be good for him to go down there and play. He has an understanding of what it's all about here. There are some things we talked to him about before he left that we want him to work on. He'll continue to improve."
Montero gets a breather
SAN DIEGO -- Miguel Montero usually does a very good job of not thinking too much at the plate, but the D-backs catcher conceded on Saturday that his slow start with the bat this year has been wearing on him.
"I just need to stop worrying so much and just see the ball, hit the ball," Montero said. "Obviously you start overthinking because you want to get the hits, you want to find the holes, and it wasn't happening. It gets into your head a little bit, even when you try not to think about it, it always stays there."
Montero has shown signs of snapping out of his funk recently. In Friday's series opener against the Padres, he homered to center, walked and had an opposite-field single to raise his average to .208.
Montero credited the success to trying to hit the ball where it was pitched, rather than an improved mental approach.
D-backs manager Kirk Gibson gave Montero the day off on Saturday against San Diego left-hander Clayton Richard.
The move was made because of the lefty-lefty matchup and to give Montero a physical and mental break. With the D-backs having blown 10 saves this year and the relievers struggling, Montero has been putting added pressure on himself.
"All the things that have been going down late in the games with the pitchers, as a catcher I know he wears it," Gibson said. "We've talked about not doing so, but I know he wears it. He's putting fingers down, and he's reflecting on what he can do differently. So I'm going to give him a little blow today."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.