With two outs in the fourth, Drew hammered a Jon Garland pitch off the side of the overhang in center. Tony Gwynn Jr. leapt at the wall to try and snare the ball, so when it hit off the overhang, left fielder Kyle Blanks had to come over and retrieve it.
"I was telling people about the wind today and when I hit it, it just kept carrying left," Drew said. "So I was like, 'Is it going to hit the overhang or maybe hit off the wall?' It was one of those things where it hit the very corner of it and I was right around second when it hit, so I knew I had a good shot when nobody was around that ball."
Dan Haren was at first base at the time of the hit and the energy he exerted coming all the way around to score had more of an effect on him than did the San Diego bats on the day.
"I had a pretty good jump, but coming around third, I made a real wide turn and I was huffing and puffing there," Haren said.
Drew did not seem sympathetic.
"Tell me about it, I was dying afterward," Drew said. "I said, 'Let's take our time when we get back out there [on the field].'"
There are two overhangs on either side of the batter's eye at Chase Field and D-backs outfielders know that if the center fielder goes under them to try and make a catch there needs to be someone backing up the play.
"That overhang doesn't come into play very often, but when it does, crazy things can happen," D-backs manager A.J. Hinch said. "I'm glad our guy hit it."
The homer gave the D-backs a 6-0 lead and allowed Haren to cruise through the seventh inning.
"Once it was 6-0, I felt good about it," Haren said.
It was the sixth inside-the-park homer in D-backs history and the first at Chase Field since July 28, 2002, when Luis Gonzalez did it off San Diego pitcher Woody Williams.