One of the things that's different about fantasy baseball, as opposed to football, is that when you're rooting for hitters, it's not always obvious what you're looking for. For example, if you're a Jimmy Rollins owner, and he draws a walk with a runner on third and no outs, are you excited that he's got a chance to steal a base, or disappointed that he lost the chance for a hit and an RBI? And it's not always clear whether going 1-for-4 with a solo home run is better than going 0-for-3 with two steals.
And it got me thinking - what's the absolute best case scenario you can get out of a plate appearance? A grand slam is always good, but you don't get any steals out of it. And a single and two steals (or three if your player miraculously steals home) might be even better, though you lose a homer and three RBI. I'd say the best case scenario is the following:
Your player comes to the plate with the bases loaded and two outs. He works a 3-2 count. The runners are moving with the pitch. He hits the ball off the wall, where it gets a true carom, and the outfielder plays it well. The three baserunners score, but your player trips while rounding first, and the throw comes into second. Your player gets back to first base safely. Essentially, he's just had a bases-clearing single. Then he steals second, third and home.
For a pitcher it's easy - an 81-pitch, 27-K perfect game. But you could throw in three passed-ball third strikes and give him 90 pitches and 30 Ks. Any more pitches/Ks is getting slightly greedy, so I'd set the maximum strikeouts for one game at 30, and it doesn't even tax the pitcher that much.