It's easy, and tempting, to separate out Stephen Strasburg's first five innings from the one that finished his night against the Reds. Until the sixth, Strasburg was leafing through the NL's top offense like it was one of the nondescript lineups he'd faced just after getting called up, zipping his fastball inside early and mostly overcoming his spotty control of his breaking ball.
But the sixth inning, the one that Strasburg couldn't finish after hanging a couple curveballs and giving up two runs, shouldn't be glossed over in an effort to paint the rookie's ninth big-league start as a dominant effort. He was still throwing in the high 90s, but appeared to be laboring, getting frustrated and losing some bite on his pitches.
That's part of the development process for Strasburg, and it's bound to happen against a lineup like this one. He hasn't faced a team as deep or as potent as the Reds, who were able to extend the inning after Strasburg retired two of the first three batters (albeit on flyouts). He started to elevate all of his pitches as the game went on, laboring more than we've seen him most of the year and angrily muttering to himself as manager Jim Riggleman pulled him from the game with two outs in the sixth.
Early in the game, though, Strasburg's delivery looked effortless; he got through the first inning in three batters after posting a 3.38 ERA in his first eight first innings - the highest he'd had in any inning. His truncated sixth inning is a cost of learning the game, and it's important for Strasburg to deal with those things. Part of what makes him so good is his penchant for damage control; he's quick to identify mistakes and stamp them out before they get repeated.
So don't call the night a huge success for Strasburg. Call it a good learning experience.