An interesting bit of baseball rules trivia applies here. If the SP does not go 5 innings, but leaves with a lead that his team never relinquishes, who is the winning pitcher?
I think most people assume it's whoever the relief pitcher is at the conclusion of the 5th inning. But that's not necessarily true. This is, as far as I can determine, the only situation in which MLB rulers do not explicitly define the winning pitcher. Instead, according to rule 10.17 (b), the decision is up to the official scorer:
If the pitcher whose team assumes a lead while such pitcher is in the game, or during the inning on offense in which such pitcher is removed from the game, and does not relinquish such lead, is a starting pitcher who has not completed (1) five innings of a game that lasts six or more innings on defense, or (2) four innings of a game that lasts five innings on defense, then the official scorer shall credit as the winning pitcher the relief pitcher, if there is only one relief pitcher, or the relief pitcher who, in the official scorer’s judgment was the most effective, if there is more than one relief pitcher.
The rules go on to provide guidance that the winning pitcher should not by default be the first relief pitcher; guidance is quite explicit that the "most effective" relief pitcher should be selected. I am not sure how WIS handles this, but I assume they just assign the W to the pitcher of record at the end of the 5th inning. If anyone finds a counterexample of this, I would be interested to see the boxscore.