"We've been struggling to score for C.C. and to be able to do it feels good," said Blake, a .228 career hitter with runners in scoring position who is batting .429 (15-for-35) with all but one of his 24 RBIs this season coming in that situation.
The Indians won for the third time in four games.
The Blue Jays lost center fielder Vernon Wells with a left wrist injury and tight right hamstring as they fell for the 13th time in their last 14 games in Cleveland.
"I felt a little something as soon as I left my feet," said Wells, who was hurt making a diving catch in right-center to rob Franklin Gutierrez of a hit in the sixth. "I hit the ground pretty hard. I couldn't breathe. From top to bottom, I didn't feel too good. I've never injured my wrist before so I don't know what to expect."
Sabathia (2-5) struck out nine over seven innings. The reigning AL Cy Young winner gave up six hits, walked two and won for the first time in five decisions at home this season.
"I just felt like if I could keep us in the game, we could battle back," Sabathia said. "I thought Casey's ball was gone. He really came through."
Halladay (3-5) lost for the fourth time in five starts and fell to 5-1 in his career against Cleveland. The 2003 Cy Young winner struck out nine and had a 1-0 lead until the seventh, when Travis Hafner and Ryan Garko singled. With Asdrubal Cabrera trying to put down a sacrifice bunt, Halladay walked the .183 hitter on four pitches to load the bases.
"The walk killed me," Halladay said. "I got caught up in trying to field the bunt and I never made a quality pitch. It was a dumb mistake. That's what changed the game."
Blake then lined an 0-1 pitch off the wall in left-center to give Cleveland a 2-1 lead.
"Halladay is as good as there is," Blake said. "He left a cutter over the plate. I think he got a little tired. To walk a guy on four pitches, you just don't see Roy doing that."
When left-hander Jeremy Accardo came on to face David Dellucci, Indians manager Eric Wedge sent up right-hander Ben Francisco to pinch hit. Francisco, recalled from the minors Tuesday, lined a double off the wall in left to make it 4-1.
Gutierrez scored on a wild pitch and Victor Martinez hit a sacrifice fly for a 6-1 lead.
"It was nice to put together a big inning against a very good pitcher," Wedge said. "C.C. put us in position to win. He did a good job of limiting them after they took the lead."
Barajas continued to torment Sabathia. The .239 career hitter went 1-for-3 and is 7-for-17 (.412) with three homers against the left-hander overall.
The Blue Jays failed to score more than five runs for the 22nd time in 23 games despite adding veteran outfielder Kevin Mench and Brad Wilkerson. Mench, acquired from Texas for cash, went 0-for-2 with a walk. He also struck out, hit into a double play and was pulled for pinch-hitter Matt Stairs in the eighth. Wilkerson, signed as a free agent after being released by Seattle, went 1-for-3.
Toronto manager John Gibbons said Wells is scheduled to have an MRI and would not play Saturday night. Wells leads the Blue Jays in homers (5) and RBIs.
Hafner came in hitting .143 (4-for-28) in his last nine games, but went 2-for-3 with a walk. ... To make roster room for Mench and Wilkerson, Toronto optioned INF Joe Inglett to Triple-A Syracuse and designated for assignment LHP Gustavo Chacin and INF Sergio Santos. ... Toronto 3B Scott Rolen went 2-for-4 and has seven hits in his last 13 at-bats. ... Halladay's season-high nine strikeouts came in his shortest outing. He had pitched at least seven innings in all seven of his starts.