BOSTON — The Red Sox already used a sixth starter this week when Brian Johnson pitched on Tuesday night. So why did they turn to a seventh starter in the last eight games with Doug Fister on Thursday?

Because they've got their eye on October.

Fister started Thursday's matinee finale against the Blue Jays because Boston wanted to give ace Chris Sale an extra day of rest following his 118-pitch outing against the Yankees last Saturday. Given Sale's second-half track record and with an eye on the postseason, the Sox are proactively looking for spots to give Sale that fifth day of rest between starts the rest of the season.

Over the course of his career, Sale has consistently been better in the first half of the season than the second half. This isn't to say he's bad in the second half: His career second-half ERA is still 3.26, compared to the first half's 2.74.

That slight downturn manifests itself most notably in September, a month in which Sale's career ERA is 3.79. In three of his five major-league seasons, Sale's carried an ERA above four in that final month; one of the exceptions was 2014, when he missed time earlier in the year and was theoretically fresher for the last month.

This first chance to give Sale extra rest wasn't planned initially. Fister was supposed to start Tuesday, with Sale going Thursday. But when Fister was needed to pitch Saturday in relief, that forced the Sox to call up Johnson for Tuesday's start. Fister is good to go Thursday, allowing Boston to give Sale an extra day after that high-stress outing against New York.

And remember, that came on three days' rest, following a high-intensity 28-pitch effort in the All-Star Game.

"I think that took a bit out of him, that week of workload," pitching coach Carl Willis said. "How he's been, I have no doubt in my mind he can come back and start on his normal day [Thursday]. But how's that going to affect him the next time?

"And so just to try to do our best to keep him where he's at, we felt like it was important to work that extra day in now."

There's another key element in this as well: Sale has never pitched in the postseason, and the Red Sox plan to lean on him heavily if and when they reach October baseball. A guy who's shown some fatigue in the sixth month of the season now has to be ready to throw in a seventh month as well.

"No doubt about it, that’s a huge part of it," said Willis. "Obviously he's been an elite pitcher, but I don't know that he's had a better season to this point in his career. Obviously there's a lot of energy there, a lot of him responding to being here in Boston and doing what people expected. We need to be mindful of keeping him physically in that spot and mentally as well."

Boston's second-half schedule does allow them to massage the time between Sale starts. He's slated to go on regular rest next Wednesday in Seattle, but the following off-day will mean he then pitches on five days' rest at home against Cleveland on August 1. After another period of regular rest, Sale could have consecutive starts on six days' rest given the club's four off days in early August. The Sox have 20 games in 20 days after that, but September off-days should allow the lefty to pitch on an extra day of rest three consecutive turns later in that month.

"The way the schedule balances out, we would look to take advantage of the off-days for all our guys as the innings are starting to pile up," manager John Farrell said earlier this week.

The Red Sox could buy Sale even more rest by either calling up a pitcher to make a spot start during that long streak in August or by swapping his spot in the rotation at some point with David Price, who has a stated preference of pitching on regular rest and, by virtue of missing the first two months of the season, may be fresher down the stretch than ever before.

Bogaerts returns

Xander Bogaerts was back in the lineup Thursday, going 1-for-4 with a double and run scored.

"I wouldn’t say [he's] 100 percent, but enough," Farrell said pregame.

Hanley Ramirez was back at first base for the second time in three games. The plan is for Ramirez to start regularly at first against left-handed pitchers.

Farrell said Ramirez's renewed defensive ability is what prevented Dustin Pedroia from having the whole day off Thursday. Pedroia went 3-for-5 as the designated hitter, including a three-run homer, while Brock Holt played second. Holt did drop a pop-up that helped Toronto to a four-run third inning.

Nevertheless, Farrell likes the versatility Holt brings back to the roster.

"His absence was felt for quite a while," the manager said. "Just moving him around the infield and getting him back in the lineup has been a good thing."

Holt went 1-for-3 with a walk Thursday.