The MLB regular season is in the books and the 2019 MLB playoff field is officially set. As 10 teams begin their October quests for World Series glory, we asked ESPN.com's Bradford Doolittle, Jeff Passan and David Schoenfield to weigh in on who is built to make deep runs, which supposed powerhouses could be most vulnerable, the breakout players to watch and much more.

Of the four wild-card teams, which one has the best chance to make a deep October run?

Doolittle: Nationals. The A's are probably the most complete of the four teams, but they'll likely have to steer past both the Astros and Yankees. As much as the Washington bullpen concerns me, the combination of their rotation and a strong, well-balanced offense makes the Nats the team most likely to navigate through the path laid out before them. They need a couple of relievers to get hot, but we've seen teams with shaky bullpens find small-sample October magic before -- like the 2018 Red Sox.

Passan: Oakland. This is no slight to the Rays; their wild-card game against Oakland is a coin flip, really, and they're mighty dangerous themselves. Or the Nationals, whose pitching staff is fairly well-suited to beat the Dodgers in a five-game series. (It's kind of a slight against the Brewers, whose incredible run is undeniable, but they are incredibly banged up, too.) It's just that the A's have the best hit-pitch-catch combination of the four -- and watching them take six of their last eight against Houston and four of their last six against New York shows they aren't scared of the elite teams they'll presumably need to beat to get to a World Series.

Schoenfield: I'll go with the Nationals thanks to that starting pitching trio of Max Scherzer, Stephen Strasburg and Patrick Corbin. Can they pitch in relief too? The problem with picking the A's or Rays is they'll have to not only navigate past the Astros, but past the winner of the Twins-Yankees series. Either way, that means beating two 100-win clubs just to get to the World Series.

Who ya got: Dodgers, Astros and Yankees or the rest of the field?

Doolittle: The combined title probabilities of MLB's power trio tells us there is a 2-in-3 chance of one of them winning it all. Sure, there is still a 1-in-3 chance they won't -- but it's not a wager I'd be willing to place. Happily, when it comes to October, nothing is guaranteed, but there is nevertheless a very clear super-tier in baseball this season.

Passan: Give me Dodgers, Astros and Yankees. All are certainly at least a little vulnerable. Minnesota could outslug New York. The A's or Rays aren't going to roll over for the Astros. The Nationals match up nicely with the Dodgers, and the Brewers are the hottest team in baseball. And those are only the Big Three's division series matchups. That said, they're still the best teams, and the math says they're a strong bet when combined.

Schoenfield: The FanGraphs odds gives those three teams a combined 63.9 percent chance of winning the World Series, so I'll stick with the Big Three. While we all understand the anything-can-happen nature of the postseason, the past three postseasons have been the era of the super teams: the 103-win Cubs in 2016, the 101-win Astros in 2017 (over the 104-win Dodgers) and the 108-win Red Sox in 2018. It wouldn't be a surprise to see the Braves or even one of the wild-card teams, but I'll bet on one of these three to win it all.

Which of the Big Three teams is most vulnerable?

Doolittle: Houston and Los Angeles could hardly look more airtight than they do right now. The Yankees' regular-season was one for the ages, given how many players had to play well for them to end up with their most wins since 2009. But now that they are closer to being the team we envisioned in spring training, the odd thing is that we don't completely know what the Yankees are. That could be a great thing for them or not. Yeah, that might be a reach, perhaps a grope, for a reason to doubt, but the point is that relative to the Dodgers and Astros, the Yankees clearly enter the playoffs with the most uncertainty.

Passan: The Yankees. The competition in the NL gives the Dodgers a clearer path. The Astros are the most talented and best team. It's not so much what the Yankees aren't as it is what the other two are.

Schoenfield: I'll make it 3-for-3 and nominate the Yankees as well. Their bullpen is deep, but not necessarily deep enough to successfully bullpen their way through an entire postseason. At some point, they'll need some outings in which their starting pitchers go six or seven good innings -- and I'm not sure I want to bet on that. Yes, Luis Severino looked good in his return and James Paxton has been very solid the final two months. The bottom line really, however: Justin Verlander and Gerrit Cole pitch for the Astros, and Walker Buehler, Hyun-Jin Ryu and Clayton Kershaw pitch for the Dodgers.

Who is one player with injury questions whose health could most change the trajectory of his team's October?

Doolittle: For all the slugging the Minnesota Twins have done this season, the amazing rookie season from Luis Arraez has played a big part in keeping the Twins' offense multifaceted. Arraez's 7.2 runs created per game ranks third on the team -- ahead of Miguel Sano, Jorge Polanco and Max Kepler, among others. So the sight of him being carted off the field on Saturday was frightening for a team that was already pretty beat up as the postseason begins. It appears that Arraez's sprain -- diagnosed as Grade 1 -- isn't too bad. Hopefully, he'll be available. For one thing, his throwback style deserves a national audience. For another, the Twins will have to put up some crooked numbers to survive the Yankees.

Passan: With a healthy and productive James Paxton backing a healthy and productive Luis Severino, the New York Yankees are a team capable of making a World Series run. With a gimpy Paxton and/or a short-stint-limited Severino compounding the loss of Domingo German following his domestic-violence incident, the burden placed on the Yankees' bullpen might be too much even for its strong foundation to weather.

Schoenfield: I'll agree with Jeff here, especially since Paxton left his final start after one inning with a sore left glute. Maybe it's nothing, but maybe it's something. Severino topped out at 80 pitches in his three outings, but after mowing down the bad Angels and Blue Jays, he walked four in three innings against the Rangers in his third start. Certainly the fastball velocity says he's healthy -- if he can give the Yankees five or six innings, that will be a huge boost to their chances.

Who will be the breakout star of this October?

Doolittle: The Cardinals' Jack Flaherty has been gaining more and more attention with each passing outing, and the timing of his breakout coincides perfectly with the onset of the October tournament. Since the All-Star break, Flaherty has been the best pitcher in the National League. His run has been reminiscent of other amazing streaks from Cardinals aces in the past, like Bob Gibson in 1968 and John Tudor in 1985. Flaherty is poised to become a national star -- and he's got the SoCal looks and the unflappable personality to exploit his opportunity.

Passan: Yordan Alvarez blitzed the major leagues by slashing .317/.406/.733 in June, his first month -- and followed that up with a .333/.419/627 line in July, .309/.425/.670 in August and .329/.424/.671 this month entering the final game of the season. Since his debut, he has been a better hitter than Mike Trout, Christian Yelich, Anthony Rendon and every one of his Houston Astros teammates, including Alex Bregman. The question, then, isn't about whether the 22-year-old is going to break out in October. It's about who's going to sit for him if the Astros make it to the World Series and lose the DH in an NL park.

Schoenfield: I guess you could argue that Ronald Acuna Jr. has already broken out, following up his sensational rookie season with a super sophomore campaign in which he hit 41 home runs and stole 37 bases. This is his opportunity, however, to do it on the big stage, and he has the swagger that reminds me of a certain Mr. October from the past.

Who is the player under the most pressure entering the postseason?

Doolittle: The Astros enter the playoffs in the favorite's seat, and while most of their players seem perfectly comfortable wearing that target, it will be interesting to see how Zack Greinke reacts to it. His postseason record to date is a mixed bag. Most recently, he was knocked out early in the 2017 NL wild-card game, then walked five over five innings in his only NLDS start the next round against the Dodgers. He has never been to the World Series, and the spotlight never gets brighter than during the Fall Classic.

Passan: Isn't it always Clayton Kershaw? While he may not look like the unstoppable, unhittable Kershaw of his prime, he's still an excellent starting pitcher. A bad playoff résumé is the lone ding on Kershaw's permanent record, with an ERA nearly two runs higher in the postseason than the regular season (4.32 to 2.44). If Kershaw summons more performances similar to the eight shutout innings he threw in last year's division series or seven brilliant innings in Game 1 of the 2017 World Series, the Dodgers have a far greater chance to do what they've been one step away from the past two seasons: win the whole damn thing.

Schoenfield: Kenley Jansen. The Dodgers have seven straight division titles and two straight World Series appearances with no titles to show for it. Jansen's postseason history the past two World Series includes a blown save and a loss in 2017 and two blown saves in 2018. If he'd done his job, the Dodgers might have two rings. Now he enters October coming off -- for him -- a poor second half. Everyone in Dodgerland is questioning whether he can do the job. So yeah, the pressure is enormous.

What is the one theme from this postseason we'll all be talking about one month from now?

Doolittle: I anticipate that by the World Series, we'll be talking about how the ability for teams to beat you in diverse ways is still crucial. Homers, walks, strikeouts -- sure. You can't win at a high level these days without a least a minimal acumen in those categories. But what separates the teams is the value added by contact hitting, defensive range, baserunning, starters who can give you innings, etc. In other words, baseball as we've always known it survives and is essential, even if it has been augmented by analytics-fueled three-true-outcomes and bullpen-heavy strategies.

Passan: How 2019 provided the highest-scoring postseason of all time. The juiced ball is real, and it is going to lead to a higher proportion of games featuring double-digit scoring than any playoffs before. Maybe the overall runs won't be the highest ever -- length of series is tough to predict -- but per-game run-scoring will set a record, there will be a public outcry from pitchers, and it will prompt MLB to spend even more time addressing what it plans to do about the ball.

Schoenfield: That stellar starting pitching is still the best path to ultimate success -- as best realized in Game 7 of the World Series, when Gerrit Cole outduels Walker Buehler in a 2-1 victory ... with Yordan Alvarez hitting the walk-off home run off Clayton Kershaw in the bottom of the ninth.