Street and Gregerson each had pitched Saturday and Sunday and the Padres were trying to stay away from them Monday.
"We knew those two were down," Thatcher said. "It's nice to know when you have your two best guys down, the coaches still have confidence in the bullpen. It wasn't going to change the game and how they make moves."
Richard almost gave the entire bullpen a day off, coming within one out of a complete game, so when Thatcher got the ball, he wanted to make sure he preserved Richard's dominant performance.
"He deserved a complete game, he pitched fantastic," Thatcher said. "He couldn't quite get that last out so if he didn't get that complete game, I had to save that win for him."
Thatcher had faced Kubel only once before Monday, a strikeout on June 2 in San Diego. The lefty knew it would be a challenge, however, as Kubel led the National League in June with 27 RBIs.
"I hadn't faced him as much as I had faced [Miguel] Montero or [Gerardo] Parra over the years but he's a good hitter," Thatcher said. "It felt good to get the job done."
Before Monday, Thatcher had made 212 career appearances without earning a save. The 30-year-old recorded 31 saves in the Minor Leagues but not more than three in a single season since 2006 because coaches didn't see him as a closer.
"Most closers are hard-throwing righties with strikeout stuff," Thatcher said. "So that was my first real save situation. We've had such good bullpens over the years. We've always had our roles so I've never been called on."
Thatcher held on to the ball and will put it with two other balls he's saved from important firsts in his career.
"It'll go up there with the first strikeout and first win balls," he said. "Right on my wall."