But Ishikawa was right there with him. He had started only two games all season before the trip, but when Posey moved from first base to catcher after the Molina deal July 1, Ishikawa jumped right in. He has hits in eight of his last nine games with a .429 average (12-for-28) during that stretch, which includes one homer and 11 RBIs.
"I went in there with no expectations, with no pressure," Ishikawa said. "Just to be able to go out and play and have fun and help the team as best I could ... and whether or not I was going to play after that wasn't up to me to decide, so I didn't feel like there was any pressure."
Ishikawa batted .261 in 326 at-bats last year at first base. But his role changed for San Francisco (47-41) early this season as he spent more time as a pinch-hitter. Ishikawa then became the best in the Majors at that, posting a .476 average (10-for-21) while also getting a few at-bats as a late-inning defensive replacement at first base behind Posey or Aubrey Huff.
The trade then changed everything.
"He's really taken advantage of an opportunity here," said Giants manager Bruce Bochy. "I knew when Buster was going to start catching, we'd put [Ishikawa] in there to get a left-handed bat in there, and he's got some huge hits for us, and he's going to get some playing time."
Ishikawa came through early in this game, getting a two-run single off Washington starter Livan Hernandez (6-5) in the first inning for a quick 2-0 lead. Posey made it 4-0 in the third with his two-run triple. Ishikawa then followed with a sacrifice fly to give the Giants a 5-0 lead.
That gave rookie pitcher Madison Bumgarner (2-2) plenty of support. The left-hander gave up one run and scattered seven hits in six innings plus one batter. He struck out six and didn't walk a batter for his second straight victory in just his fifth Major League start.
"[Bumgarner] just has real good presence and poise out there," Bochy said. "He's got a great focus out there. He concentrates every pitch. That's what you like about a pitcher, the look he has out there."
Bumgarner gave up his only run in that seventh inning. That ended a streak of 15 scoreless innings. The 20-year-old is now 2-2 with a 2.57 ERA in his four starts this year.
"I feel like confidence is a big thing, and you go out there and have a little bit of success and you get more confidence," Bumgarner said. "It's going to make the All-Star break a lot nicer than if I'd come out and had a bad game."
Still, Bumgarner needed a little help from the bullpen that's done so well in this series.
Bochy used four relievers, with Sergio Romo and Brian Wilson having good days. Romo came on with the bases loaded and one out after Washington (39-50) had already scored twice in the seventh to make it 5-2. He then struck out Josh Willingham on a nasty slider and got Ivan Rodriguez to fly out as the Nationals wound up leaving 13 on base.
Wilson entered with two on and two outs in the eighth and got the final four outs for his 23rd save as the Giants rolled into the break having won seven of their last nine games.
"We ended up having a nice road trip," Bochy said. "Great way to go into the break."