"You know what G?" Baylor told him. "Just swing first pitch."
So when Koehler fired a 94-mph fastball to start the game, Parra did what Baylor told him and swung, hitting the ball over the right-field wall for what proved to be the only run of the game as the D-backs beat the Marlins, 1-0, at Marlins Park.
"I said, 'All right, he's got more experience than me,'" Parra said of Baylor's advice.
"I'm trying to incorporate that with some other guys in their thinking, too," Baylor said. "The pitcher wants to get ahead and you can make them pay. Not all the time, but there are certain times where the guy has to think about it or maybe their scouts have to think about it."
It was the third leadoff homer of Parra's career and his fourth long ball of the season. It was also the first time he went deep on the game's first pitch.
"We've got a scouting report on him, and he's a 40-percent first-pitch swinger," Koehler said of Parra. "So, that's pretty high, especially for a leadoff man. I think he was just coming out of the gate and thinking one pitch, and he got it. Seven out of 10 times, you throw that pitch again, and he's still looking for it, and he may not hit it out. Good for him. He won that one."
That the homer was enough to win the game speaks to just how good D-backs starter Brandon McCarthy was.
McCarthy allowed just three hits in tossing his third career shutout.
McCarthy did need an assist, literally, from Parra to escape the first inning.
With two outs, Derek Dietrich walked and moved to second on Marcell Ozuna's single.
Chris Coghlan followed with a single to right and Parra fielded the ball and threw a strike to home plate to narrowly get Dietrich trying to score.
"It looked like it was a rocket and it kind of falls in with what he does -- he throws well, he catches well, he hits well and now he hits for power well," McCarthy said. "So it's kind of hard to be surprised by anything he's doing now."
After Dietrich was tagged out at the plate, D-backs infielder Cliff Pennington said in the dugout, "Parra 2, Marlins 0."
"I know I have a good arm," Parra said. "The only thing is I want to throw to the cutoff man and [catcher Miguel Montero] got it."
McCarthy wasn't the only one to toss a gem. After Parra's blast, Koehler settled in and allowed just two more hits over the next five innings before giving way to the bullpen.
In his last start, McCarthy had a shutout through the first eight innings, but manager Kirk Gibson elected to take him out with his pitch count at 88.
This time, Gibson decided to leave McCarthy in, because of the fact that McCarthy was pitching with an extra day of rest and would have another extra day before his next turn, as well as the fact that he liked how he was throwing.
McCarthy retired the Marlins in order on six pitches in the ninth.
"He said 'It's your game,' so I just kind of kept doing my thing and went back out," McCarthy said. "It's good, it's something that I want to do and be able to follow through on and go out and get three quick outs, so it's nice to know that that's something that I can start looking toward, that I can get deeper into games."
McCarthy (1-3) picked up his first win since signing a two-year deal with the D-backs this offseason.
"I was spotty at first," McCarthy said. "As good as I've felt the last few times, coming out again I just wasn't there, I wasn't sharp, but I had a focus point that I wanted to get back to. About the second inning on, I was able to get back to that and at least repeat my delivery and was able to kind of turn the game over in my favor instead of the first where everything was a little up and a little too hittable."
According to STATS Inc., the last time that a leadoff home run proved to be the only run in a Major League game was Sept. 14, 1993 when Carlos Garcia of the Pirates hit a homer and Pittsburgh defeated the Marlins. That game was stopped after six innings due to rain.
According to the Elias Sports Bureau, Parra is the first player to homer on the first pitch of a nine-inning 1-0 win since Pete Rose did it for the 1963 Reds.