Tim Lincecum and Randy Johnson against the Mariners. Johnson promised that he was "going to put one in Pinella's earhole," and no one really wanted to correct him, so this should be interesting.
If you want to know how baseball would be different if the MLB schedule were only 16 games like the NFL schedule, here's a good indication. Lincecum would start every game, and Johnson would come in when Lincecum was fatigued.
Con: less baseball.
Pro: the Giants would probably be contenders.
I gotta go with the "pro" on this one. I'll send an e-mail to Bud.