CHICAGO Six things we’ve learned during the opening month of the Major League Baseball season:

1. Unwritten rules are meant to be broken.

The unwritten rules of the game are always subject to change, just like the written rules, where doubleheaders can be reduced to seven-inning games during a pandemic and a runner is placed on second base at the start of extra innings.

Pitchers used to knock down hitters with impunity after home runs. Hall of Famer Bob Gibson once wrote he had five pitches “fastball, slider, curveball, changeup and the knockdown pitch.”

But those days are long gone. Now any inside pitch brings a pained reaction from the hitter and veiled threat of charging the mound.

So cheers to San Diego Padres star Fernando Tatis Jr., the former Chicago White Sox prospect, who ignored an unwritten rule mandating him to take a 3-0 pitch with the bases loaded and the Padres holding a seven-run lead over the Texas Rangers on Monday night in Arlington, Texas.

Tatis ignored a take sign and hit a grand slam, so the Rangers, following the unwritten rule of “don’t pile on runs,” threw at the next batter, Manny Machado, leading to a three-game suspension for pitcher Ian Gibaut and a one-game suspension for manager Chris Woodward.

“I’ve been in this game since I was a kid,” Tatis said. “I know a lot of the unwritten rules. I was kind of lost on this one. Those experiences you have to learn. Probably next time, I’ll take a pitch.”

Woodward said “a lot of unwritten rules are constantly being challenged in today’s game. ... I don’t think we liked it as a group.”

There was no need for Tatis to apologize. With so few games this year, it made sense for Tatis to pad his stats for the National League MVP race he entered Tuesday leading the majors with 11 home runs and 28 RBIs.

Dozens of players and former players sprang to Tatis’s defense, including Johnny Bench, Ozzie Guillen and Reggie Jackson. Mike Cameron tweeted: “It aint no damn rule unless u playing little league or high school because they stop the game.”

Bench tweeted: “Everyone should hit 3-0. Grand Slams are a huge stat.”

True enough. After all, they don’t call it a “good slam” but a grand one.

2. The White Sox really could use Fernando Tatis Jr.

By the way, Tatis has a 5.7 WAR in 107 games with the Padres. The Sox traded him to San Diego in the 2016 deal that brought them starter James Shields, who went 16-35 with a 5.31 ERA and had a 0.1 WAR in three seasons on the South Side. It could be the worst deal in Chicago baseball history since the infamous Cubs trade of Lou Brock for a washed up Ernie Broglio though Tatis for Shields doesn’t have the same poetic sound as Brock for Broglio.

3. Unwritten media rules need to be written.

Coincidentally, I’m making a list of unwritten rules for the Baseball Writers Association of America for the pandemic-shortened season. Here are the first five rules (please send any suggestions to @ChiBBWAA):

Always wear a shirt during Zoom calls.

If you are Zooming from your car because the team won’t let you into the ballpark early to do your job, please turn down your radio.

Make sure the team has provided paper towels in the dispenser in the bathroom at the beginning of every game.

If a writer asks the same question on a Zoom with the manager that already has been asked, he loses Zoom privileges for seven days.

Anyone who takes his mask off in a ballpark has his credential revoked.

4. The lack of hitting for average is a cause for concern.

Last year the major-league batting average was .252 with a 23% strikeout rate and .435 slugging percentage.

Through Monday, the league average was .241 with a 23.2% strikeout rate and a .417 slugging percentage. The pitchers are well ahead of the hitters, but the hitters are still crushing baseballs when they do get a hold of them.

The last time the league average was lower, it was .237 in 1968, the “Year of the Pitcher” after which they lowered the mound.

The reasons are many, but the short spring training and lack of exhibition games to work on timing are contributing factors. Is the lack of fans having an effect? Axios writer Jeff Tracy theorized that “fielders are making more plays in part because they can hear the crack of the bat. The fanless backdrop may also help them see the ball more clearly.”

It’s impossible to know whether that’s true, but it’s food for thought in this unique season.

5. Albert Pujols is nearing a significant milestone.

Los Angeles Angels slugger Albert Pujols drove in his 2,085th run Monday night, pulling within one of Alex Rodriguez for third place in career RBIs. Hank Aaron ranks first with 2,297 and Babe Ruth second with 2,214.

It’s a shame Pujols’ accomplishment won’t be celebrated, even though RBIs arguably are more important than home runs when it comes to helping win games.

At age 40 and with the loss of games this season, Pujols is unlikely to catch Ruth or Aaron unless he plays after his 10-year, $240 million deal ends following the 2021 season. Pujols said in spring training he hasn’t “closed that door,” but injuries and performance might convince him to hang it up instead of chasing the all-time RBI record.

6. A Milwaukee postseason bubble makes more sense than a Chicago bubble.

If baseball decides to go with multiple regional bubbles in the postseason, speculation is Chicago would make a good choice because of its two ballparks Wrigley and Guaranteed Rate fields.

But it might make more sense to have a Midwest bubble in Milwaukee, which has a retractable dome at Miller Park and thus can get all the games in without threat of postponement.

The only shame would be if the White Sox and Cubs were to play in a World Series in Milwaukee.