It was about this time 40 years ago — late May, early June of 1969 — that I got interested in baseball.

Harmon Killebrew and Rod Carew (and Bert Blyleven the following spring) probably had more to do with getting me hooked on the game, but the Miracle Mets of ’69 played a part in it as well.

The appearance in town last week of Jerry Koosman — the man who won Games 2 and 5 of the 1969 World Series for the Mets — prompted me to dig into that remarkable seasons anew.

If nothing else, reviewing the Amazin’s 1969 illustrates how deeply the game has evolved in the 40 years I’ve followed it — and how we sometimes miss drastic changes even as they’re occurring.

The most obvious difference between baseball in 1969 and baseball today is the offense. The Mets in 1969 scored 632 runs, 25 less than the National League average of 657. Every team in baseball scored more runs last season. The 1969 Mets allowed just 541 runs, second fewest in the league. Only one team in baseball last season came within 100 runs of that total (Toronto, 610).

Six Mets divvied up the playing time at second base, third base and shortstop. They averaged .237 and hit a total of nine home runs. Ron Santo, the Cubs third baseman, sneered that summer: “I wouldn’t play that infield in Tacoma.”

And 1969 was, in the context of its time, a relatively big season for offense. The rulesmakers, in an attempt to keep Bob Gibson from throwing 32 shutouts a year (stealing a phrase from Bill James) had lowered the pitching mound and squeezed the strike zone definition.

This worked, sort of; Gibson’s ERA went from 1.12 in ’68 to 2.18 in ’69. It was still a real good time to be a power pitcher.

A noteworthy aspect of the Mets was their intense use of platoons. They had one player with 600 plate appearances, one other with 500. Between platoons, injuries and military obligations — a feature of baseball during the Vietnam War was the large number of players in the National Guard to avoid being drafted — no Mets other than those two exceeded 400 at-bats.

Leadoff hitter and center fielder Tommy Agee led the team in homers with 26; he and left fielder Cleon Jones (who was third in the NL in batting average at .340) led the team in RBIs with 76 and 75 respectively. But the Mets had secret power. Ed Kranepool and Donn Clendenon platooned at first base; they combined for 23 homers, 73 walks and 86 RBIs.

Art Shamsky and Ron Swoboda platooned in right; they came up with 23 homers, 79 walks and 99 RBIs. Hidden production.

Platoons today are rare. A manager can only platoon so intently — Gil Hodges also used complex platoons at second and third — if he has a limited number of pitchers.

Indeed, 10 men pitched all but 21 of the Mets innings that year, and there had to have been stretches of the season in which they carried just nine pitchers. There isn’t a team today carrying fewer than 12 pitchers.

The Mets used a five-day rotation, working Tom Seaver, Koosman and Gary Gentry every fifth day and shifting others — mainly Don Cardwell, Jim McAndrew and Nolan Ryan — in and out to fill the gaps. The big three all exceeded 230 innings, even though Koosman missed almost a month.

The relief pitchers averaged well over an inning per outing.