MIAMI — Whatever is causing baseballs to leave stadiums at a record clip this season, Commissioner Rob Manfred insisted again on Tuesday that the culprit is not “juiced” baseballs but said Major League Baseball is beginning to examine the composition of bats as a possible factor and ultimately concluded we may never know the “whole answer” for this year’s spike in home runs.

None Commissioner Rob Manfred says MLB is looking into the home run spike. (Rob Carr/Getty Images)

Speaking to members of the Baseball Writers’ Association of America about eight hours before first pitch in the 88th All-Star Game, Manfred said the sport has “done more testing on the baseballs in the last few years than [ever], and we know with certainty the baseball falls within the specifications that have existed for many years.”

“We are in the process of trying to come to a conclusion as to what is going on,” Manfred said.

Baseball is on pace for 6,127 homers this season, which would obliterate the record of 5,693 set in 2000. In recent weeks, an increasing number of pitchers have asserted that the ball is different — harder, smaller and/or with lower seams — than in years past, and a pair of studies by analytics websites has backed up those claims.

Manfred acknowledged the sport was looking into which standards were most important in examining the construction of baseballs, but added: “We have used a particular testing institution for a number of years. Last year, because we thought, ‘Gee, maybe we need to go a little further here,’ we went out and hired a second expert to essentially audit and review what the first one did. I don’t know exactly what physical properties are the most important. But what I do know is we hired two really qualified sets of experts, and they agreed we were testing for the right things.”

Pressed about specific claims about the seams — which some pitchers have blamed for an apparent increase in the incidence of blisters — Manfred said he is aware of the issue and has people looking into it. He also dismissed suggestions performance-enhancing drugs could be a factor, saying the sport’s current drug testing program features more frequent and less predictable testing than at any other time in its history.

Finally, when asked which additional factors the sport is examining, Manfred brought up the issue of bats, though he stopped short of saying he suspected they are a contributing factor.

“We’ve kind of taken it for granted,” Manfred said, “that the bats aren’t different.”

Manfred also cited the “organic” changes in the way the game is played — hitters attuned to “launch angles,” pitchers who throw increasingly harder, general managers who value hitters with power and don’t mind strikeouts as a trade-off.

“There have been dramatic changes in the game, the way the game is taught, the way the game is played at the big league level,” Manfred said. “Those changes are driven by decisions of 30 general managers and field managers who are trying to win a couple more games. …

“Will we ever know the whole answer? Probably not. I think the more important question for us is to figure out as much as we can about what’s going on, and then even more important, think about what it means for our fans and whether we need to do something to manage the change.”

Among other topics Manfred addressed Tuesday:

● He said there are three “viable” bidding groups competing for the right to purchase the Miami Marlins, and all three are “essentially in the same place” in terms of their offers. Jeffrey Loria, the Marlins’ current owner, reportedly is seeking $1.3 billion for the team.

“All three groups are in the process of doing their legal work, financial structuring and due diligence, and when the process is complete the Marlins will pick the winning bidder,” Manfred said. “I’m confident that will happen in the relatively near future.”

● Both Manfred and union chief Tony Clark said the sides are having ongoing negotiations over the pace-of-play initiatives that Manfred has championed, among them a pitch clock to keep pitchers and batters from stalling. Despite an increased emphasis on keeping the game moving this season, the average game has increased to 3 hours 9 minutes, an all-time high.

“I remain hopeful that the Players Association recognizes something has changed in the game — that we’re not out to limit, change [or] alter any individual player’s career, and that it’s time for us to think together about what the game looks like on the field,” Manfred said.

Speaking separately to the BBWAA after Manfred’s session, Clark also declined to discuss specifics about the talks but said the union is willing to discuss with management “to see if common ground can be found” on pace-of-play issues.

● Manfred said the league is looking closely at how teams are using the disabled list this season, now that the minimum DL stay has been reduced from 15 days to 10. Some teams have been accused of gaming the system to use the DL as a de facto inactive list by shuttling players on and off it.

“With any new rule, our [clubs] figure out a way to manage to it,” he said. “I don’t like some of the activity. And we’re having talks about that internally.”

● He said he has had an “ongoing dialogue” with the Cleveland Indians’ ownership about phasing out the Chief Wahoo logo, which many think to be derogatory to Native Americans, but that it is unlikely to disappear completely this year.