– Rube Walker was the pitching coach for the New York Mets in the late 1960s, and he was convinced there were only so many pitches in an arm. The Mets had a precocious collection of young starters, and Walker instituted a five-man rotation to protect those marvelous assets.

The expansion franchise that had been glorified for its amazin’ futility won the 1969 World Series as the Miracle Mets, and Walker’s five-man rotation went from a radical idea to a staple of pitching that has lasted for five decades.

The Tampa Bay Rays had been making news in the first couple of weeks of this spring training for lost free agents and cost-cutting trades, and then Marc Topkin from the Tampa Bay Times reported this:

The four-man rotation with which the Rays would start the season was not merely intended for the early weeks, when there are more off days. Even the Twins have signed on to that strategy for April.

The Rays were going to run with the four-man, five-day rotation as far into the schedule as feasible, hopefully from the end of March to September. This was reported on Wednesday and it became such a big talker that Rays manager Kevin Cash was already worn out by the subject on Friday morning.

Cash does a quick media session before batting practice on the day of an exhibition game, and I said:

“Could you go through the four-man, five-day rotation strategy again?”

Cash said, “Really?” and then he repeated that the Rays would have four starters taking a turn in all five-day segments of the schedule. And, when there wasn’t an off day to make this work smoothly, four other pitchers with starting experience would be part of the eight-man bullpen and take care of the early innings of the fifth-day games.

So, the Rays use the four starters, and on the fifth day, Matt Andriese throws 40-50 pitches and gets his team to the fourth, and then Chih-Wei Hu throws 40-50 pitches. Now, it’s the seventh, and the Rays are leading 4-3 and they can go to setup men Sergio Romo, Chaz Roe and Dan Jennings, and try to get the game to closer Alex Colome.

That’s the working theory.

And then you have two more long guys — say, Austin Pruitt and Andrew Kittredge — to back up the regular starters over the next four days in the event of a short start.

I’m in, and for this reason: You get 40 appearances and 90 to 100 innings out of four relievers, rather than 50 appearances and 65 innings on average out of those spots in the bullpen.

You have gained over 100 innings from pitchers 9-to-12 on the staff, and greatly increased the odds of playing the largest hunk of the season with 12 pitchers and thus four bench players rather than three.

The Twins will go with four starters and have a couple of “bullpen” games in April, then presumably go to five starters when Erv Santana returns in May.

Twins manager Paul Molitor was asked if there’s a chance the Rays could start a trend if it works: four regular starters and “bullpen” games throughout the season.

“I suppose it depends what teams have for that fifth guy,” Molitor said. “Some clubs are six, seven deep in starters. The problem the Rays or any team would run into is obvious: If you get a couple of short starts and have to use those long guys to get through those games, and then you have to go to the minors for more pitching.

“I don’t know. It’s interesting.”

Back in the days of four-man rotations, there were relievers such as Jim Perry: He would pitch long relief, short relief and make spot starts. In 1965, he had not pitched more than three innings for the Twins in a month, and then he replaced injured Camilo Pascual and pitched 42 innings in five starts.

“I loved the four-man rotation … when I was part of it, or when I was in the bullpen and the spot starter,’’ Perry said. “I stayed ready by warming up in the bullpen, even if it looked like I wasn’t going in the game.’’

Perry used his preparation as a long reliever/spot starter to make 36 starts in 46 appearances in 1969, and then to make 40 starts and become the Twins’ first Cy Young Award winner in 1970.

Perry spends the winter in Bradenton, Fla., and was up to date on the Rays’ plan when we talked Friday.

“I know it’s a way different time, but why can’t you get 100 innings out of a relief pitcher if he has a strong arm and you use him two or three times a week?” Perry said. “I think the Rays are on to something.”