Not to pile on, but this is a shining example of how a looking at only a box score and advanced stats can be misleading.
I watched his entire start and the Padres as a team clearly came in with a plan to swing early and often, to avoid falling behind in counts. Smith did a great job of quickly recognizing it and making an adjustment, offering up pitches early in the count that looked enticing but were not easily squared up. The result was a ton of weak contact, including many pop ups. There were only three hard hit balls off him the entire game, including the home run.
I came away really impressed with the start. Not necessarily from a "stuff" standpoint, but that he has the mental makeup to recognize an opponents strategy and make effective in-game adjustments.