Tim Lincecum has nudged Dan Haren out to start the All-Star game. While Lincecum has clearly been very good this season he has not put up the numbers that Dan Haren has. Haren leads the league in ERA with 2.01, K/BB with 8.06, and his WHIP with .81. Lincecum does not even come close to Haren's stats in these catagories with a 2.33 ERA, a 4.38 K/BB ratio, and a WHIP of 1.05.
You could make the Argument that Lincecum is more of a strikeout pitcher than Haren but he only has 20 more strikeouts than him. You could also say "well he hasn't allowed 12 homers like Haren" but Lincecum doesn't play in a hitters park like Haren does. There doesn't really seem to be any justification for Lincecum starting over Haren other than the fact that he is on a winning team and has gotten national exposure. Haren is pitching for a small market team that is not playing well at all this season and that is probably the biggest reason why he is not starting at the All-Star game.