It's not fair to throw Marty Turco under the bus and say the reason the Stars are trailing 3-0 to the Red Wings is because they are not getting great goaltending, because so many elements of the Stars' game are missing.
Having said that, Turco has not been nearly as good in this series as he was in the first two. Case in point, in Game 3 Dallas fights to get to 1-1 in the first period, but then 37 seconds later the Red Wings come right back and Turco is not able to make the save on Pavel Datsyuk.
Go to the second period, the Stars fight back again and get the game tied up. This time it took eight minutes for Jiri Hudler to come down on the break away and get a goal. You could say that all kinds of break downs occurred for Hudler to get the break away, but in playoff hockey you need your goaltender to step up when the game is on the line and I'm not sure that Turco did that to the degree he needs to do it.
At the other end, Chris Osgood was tested far more in Game 3 than he was in Game 1 or 2 and he was full value. He made some really nice saves at key moments of the game to give the Red Wings the confidence they needed to break this game wide open.