A common trope in the 1970s and 1980s was that batting averages, which were low in that era anyway, actually were inflated by artificial turf.

When a ball bounced on artificial turf — which in those days  was basically plastic on a top of a thin pad on top of concrete —  it tended to bounce harder than it did on grass and ground. Many described the action the ball took as accelerating.

If only.

The law of  conservation of energy tells us that is not possible.  As one smart aleck wrote in a letter to Sports Illustrated, if the balls did accelerate when they bounced, you could put turf on all the surfaces in the Astrodome, toss out a few baseballs and solve the energy crisis.

But it is certain while ground balls were not accelerating, some grounders that an infielder might have been able to reach on natural turf did get through to the outfield on  artificial turf. On the other hands, fielders said, you had fewer tricky bounces on the artificial surfaces.

A few teams of the era, such as as the St, Louis Cardinals, were built to tale advantage of artificial turf.

So was the turf inflating batting averages?

In 1984, half the ballparks in the National League were artificial turf. In that season, every team had a lower batting average on artificial turf than on grass.

So much for that trope (at least for that one season).

The reason I know that is because a book that came out for the first time in 1985, the  “Elias Baseball Analyst.”

Elias, the official statistician for MLB, put out a book from what it called  its “secret baseball files.”

Most everybody who dabbles in baseball number crunching knows that Bill James published an annual “Baseball Abstract” starting in 1977.  By the early 1980s it was selling pretty well.

James had been after MLB to make more stats public.So Elias finally did, but they put out a competing product. Boy did they.

James’ stated reason for getting out of the annual abstract business in 1989 was burnout , but I have always thought it was largely because Elias was kicking his butt.

All of this is a long and winding way to the point of this post. It was not so long ago, that the public just didn’t have that much statistical information of baseball.

This is a follow up to an earlier post about the head-scratching move by the Brewers to cut loose Chris Carter, the National League co-leader in homers,  and replace him with Eric Thames, who has not played in the majors since 2012 but has set the KBO on fire.

Thames is neither young (entering his age 30 season), nor cheap, going for $16 million, probably twice what Carter would have cost.

And keep in mind, the Brewers are rebuilding.

Carter joins a long list of prolific home run hitters — Mark Trumbo,  Mike Napoli,  Pedro Alvarez , Adam LindJose Bautista Edwin Encarnacion and Mark Reynolds  — who have found clubs less than enthusiastic about their skill sets this off season.

While these players have drawbacks defensively and most of them are somewhat one-dimensional offensively, the lack of love for the power hitter is surprising to a lot of us, especially  with the Carter-Thames decision.

Carter is the obvious choice, the safe choice an the cheap choice. What changed?

I believe that the diminishing value for these fence-busters has to do with numbers we don’t have access to.

What started with James in the 1970s, and began mostly by asking questions because he was working off fairly limited data, and continued with the Elias books, the Total Baseball Encyclopedia, then the first data-bases on web sites, “Moneyball,” the book, “Moneyball,” the movie, “MLB Now,” Baseball Prospectus, Fangraphs and baseball-reference.com was an outsider revolution that changed the game.

And fans were a big part of it.

In 2007 and 2008, I regularly read a blog about the Dodgers on the LA Times’ site. The comments from fans were really interesting.

Of course fans second-guessing the manager and the front office has going on as long as well … there have been managers and front offices.

But the tone of the discourse was different. These were’t fans saying, “Why does he always  bring relief pitcher X ? We lose every time the bum comes in.” (When in fact X has blown just one save). The fans’ comments showed knew their stuff. They had numbers to back it up.

I can honestly look back and say that many of them would have done a better job of the X’s and O’s of in-game strategy than managers Grady Little or Joe Torre,  and they had a better ideas about player evaluation than General Manager Ned Colletti did.  (Keep in mind that X’s and O’s are only part of the manager’s job; player evaluation is only part of the GM’s job).

Yeah, there have always been fans who thought they were smarter than the guys making the decisions. Now it was plausible they were right.

By the mid- to late-2000’s, knowledgeable fans were ahead of the game.

Only a handful of front offices were data driven. The managers were still making decisions on their gut (I don’t think that is gone from the game completely.)

The number crunchers took  to the Internet and through blogs, forums and twitter shamed the baseball writers into electing Bert Blyleven ot the Hall of Fame. They opened the eyes of a lot media types.

Many in the media began pounding the drums for numbers-based decision-making. That and the success of the analytics approach, particularly with the Red Sox,  prompted  more teams to rely more on data

Now with the house-cleaning of the Diamondbacks’ front office, the last of the Luddites are gone.

But the only way you can gain advantage in a marketplace is to have better information (or a better model for interpreting the information.)

Where as Billy Beane could build teams that won 100 games a season largely on exploiting the tendency of his peers to undervalue on-base percentage, you can’t do that anymore.

A few years ago I made fun of Red Sox owner John Henry for his insight from computer research  showing that older free agents were often past their prime.  My point was a computer was not necessary to figure that out  (it had long been known).

Henry’s little morsel about an obvious point obscured something else: For some time now, teams have been buying information and as well as creating it themselves.

The recent court case and MLB’s subsequent punishment of the Cardinals after a front-office employee hacked into the Astros’ databases shows this is serious business.

How good is this proprietary information? We don’t know. We still can check baseball executive decisions’ against the mountain of data we have. We still can second guess. But we don’t truly know.

The days of armchair analysts having as good a store of information as the decision makers and a better appreciation for it are over.

It was an interesting time.