The Amazin's will implement a six-man rotation.
The objective: to keep the season innings totals in check for young pitchers Jacob deGrom and Noah Syndergaard, and especially for Matt Harvey in his first season back from Tommy John surgery. Trying to ensure 42-year-old Bartolo Colon and the injury-prone Jonathon Niese do not break down may be a positive byproduct of the expanded rotation, too.
The aim is to get each pitcher roughly 30 starts this season, instead of the 33 they would get with a five-man rotation.
The six-man rotation could continue into mid-August, pitching coach Dan Warthen said, assuming the pitchers' sharpness does not suffer with the unaccustomed extra rest between outings.
Mets officials prefer limiting the pitchers' innings through expanding the rotation to the alternatives to achieve the same objective.
The other paths to curtail innings that were discussed, according to manager Terry Collins:
• A midseason disabled-list trip, as the Mets did with deGrom last summer when he was experiencing "fatigue."
• Limiting the innings per outing by removing the pitcher after five or six innings even if he is having success.
• Piggybacking one starting pitcher after another in the same game.
• Shutting down young pitchers in September, which the Mets did with Zack Wheeler in 2013. His last appearance that season came on Sept. 17.
The six-man rotation is not unprecedented in the majors, according to Frank Vaccaro, a member of the Society for American Baseball Research, who maintains a massive database of rotation-size patterns. In fact, the Mets in 1998 used a six-man rotation for 36.3 percent of the season -- the second-most frequency of any major league team since 1993.
The Chicago White Sox in 2011 used a six-man rotation for 47.2 percent of the season. In that case, Jake Peavy returned from the disabled list and ex-Met Philip Humber was pitching too strongly to bounce from the rotation.
In the past two decades, the third-most six-man usage came from the 2003 Cleveland Indians (29.1 percent), followed by the 2004 Kansas City Royals (28.5 percent) and the 2013 Houston Astros (26.6 percent), according to Vaccaro.
In the case of the '98 Mets, the usage began when Armando Reynoso came off the disabled list in late July after a one-year absence. He joined a rotation that already included Al Leiter, Hideo Nomo, Bobby Jones, Masato Yoshii and Rick Reed. The Amazin's were contending for the wild card, and ultimately were eliminated on the final day of the season.
Then-manager Bobby Valentine figured Nomo and Yoshii would benefit because they were used to the larger rotations, which is the norm in Japan. Further, Leiter typically benefited from extra rest. Reed was exceptional that season. Jones was viewed as a starter only, not a bullpen candidate. And Valentine and pitching coach Bob Apodoca really liked Reynoso because of his control and guile, which was similar to Reed's style. So they had no obvious candidate to drop.
"It's not without precedent. That's the significant thing," said John Thorn, the official historian for Major League Baseball. "In baseball, almost everything has precedent. Even when we went from a one-man rotation to a two, or from a two to a three, it was from the worry of overuse and the shrinking number of off-days. That has been a constant since the 1870s.
"The Mets are different in that it's a 'prophylactic' use of the six-man rotation. They are trying to avoid burnout of an older guy like Colon. They are trying to take the innings limit that they've placed on Matt Harvey and stretch it out to the end, just in case they're still in contention. So I think this use of the six-man rotation reflects a measure of planning rather than an emergency situation."
Although rotation sizes steadily have expanded over the decades, Thorn does not see the evolution continuing so that six-man rotations one day become the norm. Even the Mets say this is not a long-term plan -- just something for a few months to conserve innings.
The Mets arguably have enough depth of solid starting pitching to pull it off, although the weaker links still are diluting the starts of the aces such as Harvey and deGrom.
"With the six-man rotation, I think they're doing something that's prudent and not necessarily the wave of the future," Thorn said. "I think there is a limit, because ultimately you are giving more starts to your lesser guys. This is the same complaint that was made when we went from a four-man rotation to a five. Your top starter doesn't get 40 starts anymore. You don't have Catfish Hunter completing 30-games-plus.
"This is [general manager] Sandy Alderson's plan for not having a calamity with Harvey. That is the essential thing. You can go with a five-man rotation, and all of a sudden you're on Sept. 1 and Harvey is at his innings limit because he tends to pitch deep in games."
Of course, the Mets' conservatism in recent years with innings caps for young pitchers has not prevented Harvey and Wheeler from needing Tommy John surgeries. So are the Mets just depriving themselves of a few extra starts from Harvey and deGrom without any demonstrable benefit?
Well, in the case of Harvey, conservatism with innings the first year back from Tommy John surgery is the industry norm. And Collins differentiated the current six-man-rotation plan from the past September shutdowns of young pitchers that also limited innings.
"It is something new and different. It's not the same thing we did with the other guys," Collins said. "We shut the other guys down in September. But we didn't give them the rest that perhaps they needed between starts, where we think we can do that this time."