The 32-year-old hit a game-tying home run against Reds closer Aroldis Chapman on the same afternoon Ruiz got hurt, and his bat has not cooled off since.
Since Ruiz's injury -- which landed him on the disabled list -- Kratz has nine hits, including four homers, along with six RBIs, a .441 on-base percentage and a 1.219 OPS in nine contests. He credits seeing the ball better for his recent offensive success.
"They were throwing me balls before, and I was just swinging at them," Kratz said. "Maybe now, I am hitting balls that I was missing before, fouling back before. It's that fine of a line."
Kratz hit his third home run in four games Wednesday in the Phillies' 4-3 win against the Red Sox, and he also hit two deep fly balls that just missed going out. Manager Charlie Manuel called Kratz one of the strongest players on his team.
"[Wednesday] night, he kind of hit the ball and got fooled, yet it almost went out of the yard," Manuel said Thursday. "He's very strong and he's very dangerous. If you throw the ball where he's swinging, he can put a hurting on you."
Kratz said being in an everyday role has helped him even more behind the plate than at it, as it helps him learn an opposing team's lineup better.
Ruiz is expected to return in mid-June, but until then, Kratz said he is trying to make the most of his starting role.
"You can't miss your opportunities," Kratz said. "And I had some opportunities to drive some balls that I didn't get [earlier in the season], and now I am getting some of them."
Todd Zolecki is a reporter for MLB.com. Stephen Pianovich is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.