The road to the 2019 Women's College World Series in Oklahoma City is set, and the only thing that is certain is that no one is sure what will happen. The 2019 NCAA softball season has seen the best of the best trade punches, while established stars and new faces alike have delighted and surprised.

Top-seeded Oklahoma has won two out of the past three championships, but numerous other teams want to have their say. It might be the top 16 that make it to super regionals. Heck, it might even be the top eight that make it to OKC, but nothing is certain. And if there's one thing this season has taught us, it's that something unexpected is bound to happen.

Here are the storylines we're watching as the NCAA tournament begins Thursday.

Oklahoma looks unstoppable

Shay Knighten's Sooners take a 39-game winning streak into the NCAA tournament. Courtesy Ty Russell/Oklahoma

The Big 12 championship was canceled due to rainy weather, and that's about the only thing that hasn't gone the Sooners' way as of late. The Sooners are riding high on a 39-game winning streak, just eight games shy of the NCAA Division I record of 47.

Arizona State transfer Giselle Juarez (22-0) has yet to lose a game, and fellow pitcher Mariah Lopez (17-1) is also having a standout season. In addition to the significant Oklahoma defense is the offensive power of its bats. Led by Big 12 Player of the Year Sydney Romero, Oklahoma leads the nation in home runs per game (1.90) and batting average (.365). Romero leads the team with 17 homers this season.

On top of all the stellar stats the Sooners put up this season, there are also the memories from postseasons past. The senior class, featuring Romero, Shay Knighten, Fale Aviu and Caleigh Clifton, has been there, done that. Twice. The group won national titles as freshmen and sophomores and now, after watching Florida State win a year ago, is hungry for a third.

SEC surprise

Sophomore infielder Maddie Morgan is hoping to help continue Alabama's perfect attendance in the super regional round. Courtesy Alabama

Every SEC team made the tournament field. Again. And the SEC has the most seeded teams (six). The all-encompassing presence of the conference isn't that surprising. What is surprising is the order in which the teams fell.

SEC tournament champion Florida, at No. 5, was seeded ahead of SEC regular-season champion Alabama, which was seeded eighth.

To be clear: Florida (44-15, 12-12) did not have a bad season. It just wasn't as good as the seasons we've grown used to from Florida. But going .500 in the conference and being swept at home less than a month ago by the regular-season champs and then being seeded ahead of them is going to raise some eyebrows.

Florida looked shaky through chunks of the season, but Alabama looked dominant throughout. The Crimson Tide went 18-6 in conference play and sport the most wins of any team in the field with 52. Alabama's out-of-conference schedule wasn't particularly strong, but it did post wins against Arizona and Minnesota.

The bottom line is that both SEC schools can host all the way to Oklahoma City as long as they keep winning. But don't blame the players in Tuscaloosa if they're still scratching their heads on Friday.

Kelly Barnhill's last hurrah

Kelly Barnhill heads into the NCAA tournament on a roll after allowing one run and five hits across three games of the SEC tournament. Jim Burgess/Florida

One of the most compelling storylines of the postseason is Florida ace Kelly Barnhill's pursuit of a national championship.

When Barnhill was a freshman, the top-seeded and two-time defending national champion Gators were stunned by SEC rival Georgia in the super regionals. As a sophomore, Barnhill was in the circle when the Gators fell to Oklahoma in an epic Game 1 of the championship series, 7-5 in 17 innings. In her junior season, a wild fourth inning spun out of control for Barnhill -- an error, a hit batter, a home run -- against UCLA in the Women's College World Series. It ultimately spelled doom for the Gators.

Now as a senior, Barnhill (30-11), a former national player of the year, has had to stay extra busy for the Gators. In Florida's run to the SEC championship, Barnhill threw 334 pitches over three games, including 140 in the finale, and allowed just one run.

Alongside fellow senior Amanda Lorenz, Barnhill seems determined not to make the same mistakes again.

The Pac-12 looks to end its championship drought

Taran Alvelo is half of a daunting duo in the circle for Washington. Phil Ellsworth / ESPN Images

The Pac-12 hasn't brought home a softball national championship since Arizona State did it in 2011. There are five contenders in the field this year that could end the drought. Second-seeded UCLA, third-seeded Washington and sixth-seeded Arizona all are set to host regionals and potentially host super regionals.

UCLA (46-5) has won the most national championships of any softball program, but hasn't lifted the trophy in Oklahoma City since 2010. Washington (45-7), the runner-up a year ago, won its lone title in 2009. The Arizona (42-12) drought stretches back to 2007.

UCLA is led by reigning player of the year Rachel Garcia. Garcia has a 20-1 record in the circle with a 0.98 ERA and is hitting .352 with 41 RBIs. Washington is anchored by its defense, led by Sis Bates at shortstop, and pitchers Taran Alvelo (24-4, 1.61 ERA) and Gabbie Plain (19-2, 1.32). Jessie Harper leads Arizona's offense. The junior slugger is tied for the most home runs this season with 25.

Spoiler alerts?

Count Drake's Nicole Newman on the list of players you'd rather avoid during the NCAA softball tournament. Courtesy Dylan Heuer/Drake

Remember how we said the only certainty about this bracket is uncertainty? Here are a few regionals that could register high on the drama meter.

Seventh-seeded Minnesota (41-12) is hosting a regional for the first time since 2014. Heading to Minneapolis are Drake (42-14) and Georgia (40-17). Drake features ace Nicole Newman, who owns the NCAA single-season record for perfect games with five. She set the record over the weekend, and incredibly all five of those perfect games happened since March 30. As for Georgia, we point back to the blurb about the SEC. It's what we call battle-tested. Still, Minnesota, which was famously snubbed by the committee in 2017, was overjoyed with the seventh seed. "I had tears. No words," said senior right fielder Maddie Houlihan, a four-year starter and one of eight remaining players from the 2017 team. "I was so, so beyond excited. We kind of had some realistic expectations of where I thought we might be, but you never really know what's going to happen."

Fellow Big Ten team Michigan (43-11) got the No. 15 seed. That's the good news. The bad news is that James Madison (47-7) is on its way to Ann Arbor. The Dukes have one of the best pitching duos in the country in Megan Good (19-5, 1.49 ERA) and Odicci Alexander (22-1, 1.97 ERA). Did we mention they both can hit, too? They've combined to hit 29 homers on the season.

Sure, Florida got the 5-seed, but it also got an upset specialist in the form of Stanford (32-18) heading to Gainesville. The Cardinal have wins over LSU, Michigan, Northwestern and UCLA.

Pat Borzi contributed to this story.