SAN DIEGO -- When his outing was over, Madison Bumgarner retreated to the D-backs’ clubhouse Friday night. Alone with his thoughts, the veteran left-hander replayed his five-inning start over in his mind, searching for an explanation for what went wrong.

When the game was over, with the Padres coming away with a 5-3 win at Petco Park, Bumgarner was no closer to a solution.

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"I've been trying to think since I came out of the game and look and find some answers," Bumgarner said. "But it was like today was just one of those days. It's not … I don’t know. I don't have anything for you. I've thrown a lot of games worse than that and had far better results. So I don't know. That's just part of it."

Bumgarner came out of the gates throwing hard with his fastball reaching 95 mph in the first inning, one mph faster than his fastest pitch this year. In fact, his average fastball velocity has ticked up each month this season.

In the previous two seasons when he would struggle, Bumgarner could point to one thing or another as a reason. Friday left him confused.

"Especially when I've got probably the best stuff I've had for seven years or more," Bumgarner said. "Those are definitely more frustrating. At least if you knew what it was, you can go work on fixing it. This is one where you just almost have to flush it."

It didn't start out that way as Bumgarner retired the Padres in order in the first inning.

The second inning, though, started off with a throwing error by Josh Rojas at third base, and things spiraled from there as the Padres scored three runs.

"I thought Bum came out aggressive, on the attack," D-backs manager Torey Lovullo said. "He had a really good first inning, the fastball velocity was as much as we have seen it. Obviously, he's been feeling good, and I know that he's put a lot of hard work in behind the scenes.

“I think the second inning just kind of unraveled on us after the miscue at third base. Those are the little things that we've got to really tighten down. Our margins are just so small. Our margins in every area of play are so small, and when we make mistakes they can be costly. And in this case, I think it led to three runs."

The Padres scored another two runs in the third inning. While it wasn't necessarily pretty after that, Bumgarner managed to keep them in check over the next two innings before departing.

Bumgarner wound up walking four while striking out three.

"There were some times where I just wasn't finding the strike zone and others where I would just miss a few inches off," he said. "A lot of times, I was just trying to throw it in the strike zone anywhere.

“Like I told you after my last start, I was trying to be aggressive in the zone and that led to making better pitches. And I was still trying to do that today. I lowered my expectations of hitting the corner or third to just anywhere in that box, and I just wasn't finding it a lot of the time.”

Neither was Bumgarner finding many answers after. The game may be over, but his search will continue.

"I don't know, maybe if I tell you that [my stuff was good] again after a bad game I need to reflect on everything that's going on," Bumgarner said. "There's only so many passes where you can say your stuff was good and the results weren't."