Major League Baseball commissioner Rob Manfred declared the sport's "steroid era" all-but over Monday but said new US betting laws will provide another challenge for the sport's integrity.
On the eve of the 89th All-Star Game, the first staged in the US capital since 1969, Manfred hailed the impact of doping test protocols that include blood tests, biological profiles, random testing and an investigative staff.
"I don't believe there is the widespread use of performance-enhancing drugs in baseball any more," Manfred said. "I feel good that we've done everything humanly possible to prevent the use of performance-enhancing drugs.
"But we will remain constantly vigilant."
Major League Baseball stars Alex Rodriguez and Mark McGwire admitted taking performance-enhancing drugs and steroid accusations tainted some of baseball's top stars, including US home run king Barry Bonds and pitcher Roger Clemens.
Only after pressure from US lawmakers did the major leagues ban steroids and begin a tougher testing policy with severe punishments in 2005.
"Baseball has the best testing program, not only testing but drug program, not only in professional sports but all of sports," Manfred said. "If you talk to the Olympic groups, WADA (World Anti-Doping Agency) and USADA, they will tell you ours is the best."
The latest issue facing Manfred, who became commissioner in January 2015, is legalized sports betting, which thanks to a Supreme Court ruling is now open on a state-by-state basis.
Manfred, who said he disliked seeing references to oddsmaker lines on European football telecasts, would prefer a federal system compared to 50 state ones but vows MLB employees won't bet on baseball no matter what's legal.
"The challenge for us is to make sure... those laws develop in a way where we can protect the integrity of the sport," Manfred said. "We want to be careful our product retains a certain pristine quality.
"Anyone who works for Major League Baseball, whether it's legal or not, will not be allowed to bet on baseball. We'll always have this rule."
Retired Cincinnati Reds star Pete Rose, the all-time major league leader in hits and games played, was banned from baseball for life in 1989 for betting on baseball while manager of the Reds.
Rose, 77, applied for reinstatement to Manfred in 2015 but was rejected, the commissioner saying to allow Rose back was an "unacceptable risk."
"I ruled on that request for reinstatement," Manfred said Monday. "That's where it's at as far as I'm concerned."
- Stormy weather -
Manfred meanwhile cited record numbers of April rainouts and cold weather for games as reasons major league attendance is off 5.5 percent this season.
"We're playing real attention in case there's something else out there," he said. "But we think it's the weather."
Major League Baseball enjoyed $10 billion in revenue last year, according to Forbes magazine, and Manfred says "baseball is in a great spot."
"We have a generation of young players that are as talented as any in decades," he said. "We're really positive about our product."
Manfred says it's "100 percent possible" there could be a woman umpire or woman commissioner in Major League Baseball's future and didn't rule out the possibility of a female player, noting girls playing on boys youth teams.
"There are female athletes out there that are phenomenal," Manfred said. "So who knows?"
Manfred sees eventual expansion from 30 to 32 clubs but says it is a "back burner" issue will not happen until stadium issues in Oakland and Tampa Bay are settled.
"Expansion would also give us a look at how we're aligned and our playoff structure," Manfred said. "I can see us one day at 32."
Mexico and Canada are along areas where Major League Baseball will look when the time comes, including Montreal, which lost the baseball Expos in 2004 to Washington after 36 seasons.
"It's a big city with a baseball history," Manfred said. "It could be a great city for us."