I would definitely start him because the Dodgers have one of the weak offenses and it is in LA, one of the most pitcher friendly parks.
Ortiz is the type of pitcher who tends to thrive on pitching himself into and out of jams, so he will always walk alot, give up alot of hits, and have a high WHIP. However, he usually has a respectable ERA and decent win totals, especially playing for a hot Atlanta team. If his control is really bothering you, I would suggest trying to trade him for another comparable pitcher. I had him and there was this idiot in my league that "needed" him to complete his collection of the entire Atlanta starting rotation. So, I traded him for Matt Mantei (I needed a closer) and Jay Payton.