Major League Baseball is in the early stages of drafting an operating manual for a playoff bubble, the same initial step it took in drawing up its coronavirus protocols for the regular season and another sign that the league intends to pursue a more strictly contained postseason, sources familiar with the situation told ESPN.

The league's original operating manual became the heart of the 113-page document that outlines MLB's rules and regulations during the 2020 season. While the league has not settled on staging a postseason bubble in which the it would use neutral sites to significantly lessen travel and restrict movement in hopes of preventing a coronavirus outbreak, MLB continues to discuss potential sites and formats.

The 16-team postseason could begin in two geographic areas with two sites each, with Southern California and Texas emerging as early favorites and New York and Chicago/Milwaukee also possibilities, sources said. Following the wild-card round, the two National League division series could be played in San Diego and the two American League division series in Arlington, Texas, mirroring the two-hub format being used by the National Hockey League. Baseball could move its league championship series to a single site or maintain the two hubs until the World Series.

MLB has consulted with the NHL about the benefits and perils of its bubble, according to sources, and information sharing among the major sports leagues on coronavirus protocols has become standard. The commonalities between MLB and the NHL, however, make it a clearer match than with the NBA or NFL. And as hockey's bubble continues its successful run, MLB will seek insight from the NHL about how baseball in October may look.

Here are answers to some questions that illustrate why hockey has emerged as a good model for baseball.

For baseball fans who might not be following, where are NHL playoff games being played?

The NHL chose two Canadian cities as its hubs: The 12 Eastern Conference teams are in Toronto, while the 12 Western Conference teams are in Edmonton. By the conference finals -- which should begin in early September -- the entire tournament will be consolidated in Edmonton.

The NHL briefly explored using true neutral sites, such as New Hampshire or North Dakota, but quickly determined it needed the back-end capabilities of NHL rinks to maintain the integrity of the Stanley Cup playoffs. The league had hoped to choose one American city and one Canadian city, and was very close to picking Las Vegas. However, when cases spiked in several U.S. states, the league pivoted to Canada, which has much lower COVID-19 numbers.

How much of a true bubble is it, as compared to the NBA's self-contained "city"?

While the NHL is technically in two major cities, the league has created enclosed "secure zones," largely independent from the rest of society. In each city, the NHL installed fencing around areas that include not only the arenas, but hotels and some restaurants and bars. (The only caveat is that hotel, restaurant and arena workers in the secure zones are allowed to leave and go home at night, though they are tested for COVID-19 daily.) Since the area is enclosed and has security, there aren't any autograph seekers or gawkers. Regular citizens can't just walk in and interact with players or even get close to them. The NHL is also arranging to have some controlled excursions for players -- for example, golf outings at a closed course -- but with a condensed schedule through the first two rounds, teams haven't taken advantage of that yet.

As the NHL and NHL Players' Association negotiated, what were the biggest points of contention?

To be honest, there weren't many. The NHL and NHLPA were incredibly collaborative throughout the entire process -- and even knocked out a CBA extension during their pause (which was surprising, since Gary Bettman has already had three work stoppages in his tenure as commissioner). There was a shared motivation to find a solution, and a lot of it was financially driven. The league stood to lose more than $1 billion if it couldn't complete the season, and because the NHL has an escrow system, that meant significant money being subtracted from players' paychecks next season. There was also a shared understanding that visibility is important for hockey, in the sport's ever-growing quest to expand its U.S. footprint. A work stoppage wouldn't behoove anyone, especially as the league is up for a new U.S. TV contract in two years, while welcoming its 32nd team, Seattle, for the 2021-22 season. At the GM meetings in Boca Raton, Florida, in March, shortly before the coronavirus shutdown, Bettman boasted that the NHL was "healthier than ever." Nobody wanted to stop that momentum.

What was the entry process for those inside?

Teams traveled to the bubbles on private charters from their playing cities and were tested immediately upon entering. Canada has a strict 14-day federal quarantine for any visitors crossing the border, but the NHL worked out a deal with the government that essentially said the "secure zone" would serve as their quarantine. The NHL also instituted several buffers. For example, teams weren't able to interact with other teams (eat at the same restaurants, for instance) for the first few days inside, though those restrictions were eventually loosened.

There have been times when players have left the bubble. Lars Eller of the Capitals, for example, went home to be with his wife, Julie, as she delivered a baby. Eller rejoined his teammates, but only after following a strict quarantine protocol for a few days -- essentially, he couldn't leave his hotel room and had to test negative for four consecutive days. If a player must go to the hospital for medical attention, that also means he is leaving the bubble. Re-entry and quarantine protocols are determined on a case-by-case basis, depending on how much exposure the player might have had.

How often are those involved tested for coronavirus?

Everyone inside the bubble is given a 30-minute window for daily testing appointments, which are set up in the team hotels. Around 1,500 samples a day are collected from those inside the bubble, and couriers bring them to labs for processing. Results are available within 24 hours, and the league has publicly shared results on a weekly basis. To date, there have been zero confirmed positive tests.

Considering the tests retail for more than $100 each, it's an endeavor Bettman conceded will cost the league millions of dollars, but was absolutely essential if they had any chance of playing hockey this summer. The NHL was sensitive to ethical concerns of procuring tests -- especially the perception that the league was taking them away from the public -- and that's one of the reasons they're in Canada, as infection rates were lower and the league didn't feel as though it was diminishing the public supply.

Every player in the bubble is tested for COVID-19 daily.

Take a look at how the process goes. #StanleyCup pic.twitter.com/1gxs5ZZ908

— NHL (@NHL) August 15, 2020

Is the bubble for players and staff only, or are family members allowed in?

For the first three rounds of the playoffs, teams are allowed to bring only 52-person traveling parties, which does not include family members. The NHL and NHLPA agreed that players' families could join them in the bubble for the conference finals; by that point, the number of people in the bubble will have dwindled, and the NHL will be operating only out of Edmonton. The NHL is still finalizing details, and the NHLPA is currently reaching out to teams, gauging interest on how many additional people would like to come. The plan is for immediate spouses/partners and children to be able to join players in their hotel room.

Integrating new people into the bubble brings an inherent risk, but there's a plan to mitigate it. Seven days before departure for the hub cities, family members will need to self-isolate (i.e., stay at home as much as possible and avoid unnecessary interactions with non-family members) and produce three negative tests, 48 hours apart, over the seven-day period. Upon arrival, family members would have to quarantine in their own hotel room (not in a room with the player) for four days until four negative tests have been confirmed. Once the quarantine is over they can be in the same hotel room as the player. While in the bubble, family members would be subject to daily testing.

What is an average day like for a player?

I had one player tell me life in the bubble is "like being at a youth hockey tournament, but knowing you might be there for two months." There are typical road trip staples: team meetings and film sessions, morning skates, games and team meals. The NHL tried to inject enough entertainment to keep players from feeling too cooped up, but the offerings aren't exactly as lavish as we've seen from the NBA in Orlando. In each bubble, the NHL set up food trucks (and a Tim Horton's truck because, Canada) though players have access to a handful of restaurants, or do contact-free delivery or room service.

Each arena features suites for players, coaches and execs to catch other teams in action. In Toronto, BMO Field, the home to Toronto FC, is included in the bubble, and players are able to have what's essentially recess on the field -- kick or throw around a ball (spikeball is especially popular) or relax. In Edmonton, players have access to the CFL stadium. Ping-pong tables and golf simulators are set up in both bubbles. The Golden Knights say they have a player-led "fun committee," though the first activity, a viewing of "Semi-Pro," had the feel of a middle school sleepover party.

Team movie night in the bubble pic.twitter.com/JTt2dumFqs

— Nick Cousins (@Cous27) August 13, 2020

"Yes, having amenities is great, and yes, having theme nights that are a hit on social media are great, but we're here for one reason and that's to win hockey games," Avalanche defenseman Ian Cole said. "People are like, why don't you do more fun things? And, yeah, we do fun things, we hang out with each other, but it's not like we're searching for off-the-wall activities. ... Eventually we're going to have four games in six days here. What are we really going to do on our off days here? Play golf? Are we gonna go play spikeball for six hours? Realistically, no."

There have been a few snafus early on. Some players weren't too pleased with the initial food offerings, but the NHL adjusted. The air conditioning went out the first week at one of the hotels in Edmonton. But the players haven't done any griping in public. While part of that is due to hockey culture -- guys never want to call attention to themselves or be perceived as divas -- there is also a shared understanding that doing anything remotely normal in 2020 is hard, and everyone is doing the best they can.

What are the penalties for breaching the bubble?

They're pretty steep! The NHL said that violating protocols, which includes leaving the bubble without permission, could lead to "significant penalties, potentially including fines and/or loss of draft picks." If a player refuses to be tested, he will be forbidden to play and also could be removed from the tournament.

How much is this costing the league?

We haven't been able to nail down an exact figure from the NHL, but make no mistake: This is a costly tournament. (Consider that testing alone is a multimillion-dollar expense.) We do know that the league stood to lose more than $1 billion if it could not complete the season, and according to estimates shared with the NHLPA, it could recoup about half of that from staging this tournament -- a lot of the money was tied in to fulfilling local TV contract obligations, which is why the qualifying round even existed. Estimates peg the tournament cost at upward of $100 million. One team president said the league would "be lucky if they came close to breaking even." But it seems from a business perspective, everyone agrees: For the visibility of the league and long-term growth, it was the right thing to do.

What would the NHL do differently were it to go back in time?

NBA commissioner Adam Silver told Sports Illustrated he wishes he found a way to include all NBA teams in the Orlando restart. The NHL doesn't necessarily feel the same way. It did include eight extra teams from its usual 16-team playoff format -- again, to help fulfill local TV contracts -- but nobody is arguing that the stigmatized seven (aka the league's bottom dwellers) should have been there. It is less than ideal that players on those teams could go 10 months -- or more -- without playing a meaningful hockey game, but that's just a casualty of the pandemic.

The NHL did take a huge risk in opening training camps in 24 cities -- many of which were still experiencing high COVID numbers -- without a bubble environment. If the tournament was planned today, the NHL may not go that route. But it was something the league agreed to early on in negotiations with players. If families weren't going to be included in the bubble, players wanted as much time at home with their loved ones as possible. While players were tested regularly in training camp, they also had the freedom to leave the rink and go to restaurants, ostensibly bars, and interact with whomever. The fact that the NHL was able to get through training camps largely unscathed is a very lucky bounce.

Why has it worked?

Patience was a huge part of it. The NHL was diligent in planning; waiting until as late as possible to name the hub cities allowed it to pivot from Las Vegas to Canada. A shared motivation between the league and players to not only plan the tournament, but adhere to the rules, has also been crucial. Overall, communication is strong. And, of course, it doesn't hurt that the NHL chose Canada. "I mean this sincerely, with total love and respect. I'm sitting in Toronto and I'm not trying to be a smug Canadian," said Dr. Isaac Bogoch, an infectious disease expert who consulted with the NHLPA. "Obviously, the numbers are really high in the United States, and things are in pretty decent control in Canada. Canada's population is close to 38 million people, we're getting about 200-400 new cases per day. It's not perfect, but it's pretty damn good."

Is the NHL doing anything to re-create home-ice advantage or give better seeds a reward?

During games, not much. If not for uniforms or home teams getting the last change, you wouldn't be able to differentiate who is home and who is away. In the arena, goal songs are played for both the home and visiting teams, which seems somewhat sacrilegious but you get used to it.

Off the ice, there were some minor advantages. Teams needed to be split into two hotels during the qualification round, and the better seeds got the nicer hotel (Hotel X in Toronto, JW Marriott in Edmonton) while the lower seeds got the slightly lesser accommodations (Royal York in Toronto, Sutton Place in Edmonton). Once teams got eliminated, lower seeds were able to move into the better hotels.

What about practice time? Where are players able to train when they are not playing?

The NHL made sure it chose two cities that had enough sheets of ice for teams to practice. In Edmonton, the practice rink is a 25-minute drive away, and players travel there via a team bus, escorted by security. The NHL also made the decision not to allow any teams to have morning skates at the main arenas, to help preserve the ice.

Does the level of play/intensity feel like playoff hockey to players and observers, and is there anything MLB should take from this?

It's been impressive how quickly the players have been able to amp up to playoff intensity. That said, having no fans has been an adjustment for some players. A common refrain heard in the tournament, as echoed by Boston winger Jake DeBrusk on Monday: "You have to create your own energy."

Most teams have been able to adapt. One of the most exciting games of the tournament so far was Tampa Bay's five-overtime win over the Blue Jackets. Afterward, coach Jon Cooper discussed the strange dynamics: "You know, the one sad thing about tonight is that you have a game and an effort put out by the two teams that we witness tonight and there was actually nobody in the building to witness it. And to see the excitement on the players when they scored, regardless if there were fans in the building or not. That's one thing I'll remember is you still turn the clock back and they're still a bunch of kids and they competed their asses off and they get damn excited when they score, especially when they score in the fifth overtime. It just brings you back to the frozen pond. I don't know, it was a pretty cool moment."

From a TV perspective, the NHL has created a fantastic product. The synthetic crowd noise sounds natural, other than the lack of fans yelling "shoot" anytime a player crosses the blue line. The way they covered the empty seats with tarp stands out, and that's something MLB could draw from. The NHL created a stage where your eyes are drawn right to the action, and you are not distracted by the fact the game is in an empty arena.

A five-overtime game threw off the schedule for other teams. Is there another way to schedule games to avoid that issue?

The NHL could have scheduled morning games to help avoid this, though it may have received some pushback from television partners. The issue with the five-OT game was that once it ended, based on the safety protocols, it would take about 90 minutes to turn over the arena -- including a deep disinfecting of benches -- before the next warm-ups could begin. So yes, it did throw off the schedule for a day. But it's playoff hockey, and it's 2020 -- things happen! Everyone seemed to adapt just fine.