Why is Maton considered the winning pitcher?

I think I understand how, officially, the winning pitcher of a game is determined (the pitcher who last pitched prior to the half-inning when his team maintains the lead that it never relinquishes). This would make Maton the winning pitcher of today’s game against Cleveland. But he only pitched one inning, and didn’t have anything to do with keeping them down through the rest of the game. What is the common sense reasoning behind considering him the “winner”?