Starting pitchers are creatures of habit, and the habits of J.A. Happ have served him well this year. When he pitches on his normal four days' rest, his ERA is 1.74. Five times he has worked on five days' rest. In those games, his ERA is 8.25.

That's a tiny sample size, of course. A few more starts on extra rest might significantly reduce that number. And the Blue Jays' left-hander will indeed get a few more starts on extra rest.

So will his rotation mates. Largely to protect the arm of their ace, Aaron Sanchez, the Blue Jays have switched this week to a six-man rotation. Happ will start today (Wednesday), and with Thursday's off-day he will make his next start on six days' rest in a week.

Pitching coach Pete Walker said the new rotation sequence lines up this way: after Happ and Thursday's day off, Francisco Liriano, Sanchez, Marcus Stroman, R.A. Dickey and Marco Estrada will follow.

Each pitcher will need to make adjustments to deal with the extra day(s) between starts. Talk to Walker and his starters, and they'll say the change is no big deal. Perhaps not. But collectively, those six starters have fared much better on four days' rest this season. Their combined ERA on four days' rest is 3.41. On five days' rest, it's 4.51. Of the group, only Liriano has pitched better with an extra day's rest.

Six-man rotations are typically short-lived. For this one to endure, all six starters will have to pitch exceedingly well. There will be tweaks along the way, especially to keep Sanchez from taking his innings total too far into uncharted territory. It would not be surprising to see more changes and new plans.

When general manager Ross Atkins told the media about the six-man plan in Houston last week, he said all six starters were on board. That consensus came not from a summit meeting of the pitchers but from individual sessions that Atkins, manager John Gibbons and Walker held with each rotation member.

If there were individual misgivings, they were outweighed by an overwhelming communal desire to keep Sanchez in the rotation, both because of his splendid performance and because the chatter about sending him to the bullpen had become a distraction.

"We didn't necessarily have a round-table discussion about it," Happ said. "I think it was a situation where it was kind of like on-the-fly every day—it seemed like we were kind of waiting to see what was going to happen. It wasn't necessarily like, 'How does everybody feel about this?' I think everybody felt like, with Aaron in the rotation, it makes us a stronger team, so I think that's why people felt like everybody was good with it."

So the adjustments, minor though they may be, have begun.

"I don't know how long a six-man rotation has ever been done before," Happ said. "I don't know that I anticipated it being for the next two months. Short term, I don't have any issues with it."

Each year, a team or two will trip lightly into the six-man experiment, sometimes to give a tired pitcher extra rest or to insert a hot minor-league pitcher into the mix and see how fares.

Houston used six starters briefly in May. The Cubs did it fleetingly in July. The Phillies did it last September.

In the Jays' case, the life cycle of the experiment will depend on several factors, not just how well Sanchez holds up.

Estrada has battled back problems all season. Stroman is on track to hit 207.1 innings, 51 above his previous ceiling.And Happ, a 33-year-old veteran whose 15 wins lead the league, is projected to finish with 196 innings. His previous high was 172 last year.

Dickey always seems a lock to reach 200 innings. Liriano has approached that plateau twice in the past 10 years. For the other four starters, one could argue that the extra rest might do some good.

Walker, the pitching coach, believes that. So far, he says, he sees no evidence of fatigue in any of his starters. And he insists the adjustments they face are not significant.

"Maybe the day after they start, they completely take a day off from throwing and just flush and then get on their normal routine the following day," Walker said. "They'll have to make a few adjustments, but I think the pros outweigh the cons at this point, as far as trying to keep guys strong physically."

When pitching on long rest in the past, both Liriano and Happ have occasionally thrown two bullpen sessions between starts.

"I'll probably take one day off without doing anything," Liriano said. "Just run and play catch. I might throw a bullpen probably twice, just light ones."

For Liriano, the key is not to feel too strong when he enters his next start.

"When I feel too strong, I try to do too much, just rushing," he said. "That's why I throw two bullpens between starts."

For Happ, pitching success depends a lot on "feel," which in turn can depend on maintaining a consistent routine when he's on a roll. (He's on one now, having won his past eight decisions.)

"There are times when you can't wait to get back out there," he said. "You just want to stay right where you're at and keep yourself in the bubble and keep that feel. Then there are times when it's the exact opposite. Those are times when sometimes it can be good to have an extra day to throw that extra bullpen or get that extra work in."

An injury or an ineffective starter could change the six-man plan. Days off or rainouts could change the rotation sequence.

"There may be an adjustment a time or two throughout the next six weeks," Walker said, "but for right now, it's going to stay status quo."

Until last week, the Blue Jays appeared committed to an experiment without apparent precedent: moving their ace to the bullpen in the heat of a playoff race. Now they seem committed to another untested scheme: adding a struggling pitcher from the National League to the rotation, thereby giving their top starters fewer starts while presumably protecting their health.

The gamut of possibilities is obvious. Management is counting on six well-rested starters to carry them to the playoffs. If they make it, they can get by with four, one of whom, they desperately hope, will be Aaron Sanchez.

Consider the dice rolled.

And consider the first complaint registered, mild though it may have been.

Pitching on five days' rest Tuesday night, Estrada walked four and gave up seven hits (although only three runs) in five innings during a loss to Tampa Bay. Afterward, he said he felt "rusty."

Asked whether the extra day contributed to the rust, Estrada seemed to say yes, adding quickly that he wasn't using that as an excuse.

But he made it clear he faces an adjustment to the longer layoff.

"I've got to do a better job, I guess, getting ready, maybe throw longer bullpens or just throwing (more) in general," he said.